Calibrating Evolution of Transformative Tourism: A Bibliometric Analysis

Transformative tourism (TT) has been gaining a lot of attention over the past few years due to its power to transform both the individual and the world we live in, in a positive way. Although presently consisting of a plethora of studies, transformative tourism lacks the lens of a bibliometric approach to track its growth in a more objective and quantitative manner. In this article, a total of 250 publications were analysed using several bibliometric performance metrics, science mapping techniques, such as citation analysis, co-occurrence, and co-authorship, as well as enrichment procedures. By combining these methods, the study identifies the most prolific journals, reference studies in the field, key authors, collaboration patterns, geographic distribution, preferred methods, major research topics, as well as an overall research timeline in this area of study. Findings suggest that transformative tourism could become the heart of tourism in the upcoming years as it begins to take deeper roots through new junctions and discoveries, appealing to more researchers and practitioners, with the literature on TT thus gaining momentum. This paper contributes to fill a research gap and capture the evolution of the fast-growing concept of transformative tourism using bibliometric analysis. The article provides useful insights as well as further research directions for both researchers and tourism practitioners interested in this field of study.


Introduction
Travel and tourism, representing one of the fastest growing sectors in the world, have long been connected to the idea of transformation [1], considered to be a fertile ground in transformative learning [2] as tourism experiences have the capacity to influence and change people's lives [3,4] and function as drivers for personal change. Combined, both tourism and transformation can alleviate the problems the world is facing right now, by shifting people's perspectives and raising their self-awareness, all towards a better future as "human survival is inextricably linked to human transformation" [5]. The ability of transformation to happen anywhere [6] and anytime due to its pure reliance on the individual [7] and various contextual stimuli [8], rather than a specific type of tourism [9], along with adding up its unquestionable cyclical essence as a process and not as an end outcome [10], augments and attributes a chameleonic nature to transformative tourism.
Mostly built upon Mezirow's transformative learning theory (1991) theoretical framework [11], the TT concept has shapeshifted over the years as academics continually discovered new facets to it. After the introduction of "transformative travel" in 1998 by Jeffrey Kottler [12], the concept gradually turned into a growth of interest and ramified from a scant amount of tourism types, such as adventure tourism [13], backpacking tourism [14,15], international sojourn [16], dark-tourism [17], and extreme sports [18], with cross-cultural [19,20] to changed beliefs from business tourism not being suitable for transformation [21], to demonstrating its transformative power [22], to even having echoes in mass tourism [23]. Several perspectives were introduced, whereas from relying mainly on a tourist's point of view [16,24], continued as a co-creative experience including host perspectives [25][26][27] and even organisations [28,29]. TT has zigzagged from its ability to foster transformation only in extraordinary trips and places [30], to experiencing liminality and therefore transformation even in familiar contexts [31]; from happening purposively [7,32,33] to incidental occurrences of transformation [34]; from pointing out a lack of feelings and emotions in Mezirow's theory [35], to slowly introducing the role of emotions in transformation [36][37][38].
Later research shows a far more elaborated facet to TT as it implies a practical approach. The last three years of studies constitute around 40% of total publications related to the subject and integrate aspects such as the design of the transformative experiences [39][40][41], models of transformation processes [6], analysis of organisational approaches [29,42], creation of a transformative travel experience scale [43], product development [44], identification of facilitators and inhibitors in TT [22], transformative leadership [45] and proven correlation between transformative tourism and improvement of sustainability [46]. The same pattern is followed by the three review publications related to the subject, starting from the transformative learning theory [47], to nature-based experiences [48], and ending with a complex conceptualisation of transformative tourism experiences [49].
The back-and-forth literature exhibits the endless potential of growing the concept of TT. Given the importance of transformative learning on shifting individuals' mindsets [50] and tourism experiences on changing lives of consumers [3,4], along with Pine and Gilmore's speculation upon transformation being the next trend on the world-wide scene [51] as a successor to the experience economy [52], scientific advancement in this field of study is conspicuous and therefore requires to be measured. However, to date, a bibliometric approach of published literature on TT has not yet been conducted. Hence, the purpose of this study was to deploy such analysis on papers published in four databases over a period of twenty-four years , to synthesize the tourism literature on transformative tourism as well as to grasp the evolution in this area of study. This paper aimed to respond to the following research questions: (1) What are the general characteristics of studies related to TT? (2) What is the actual quantitative and objective state of knowledge regarding TT? (3) How has the research interest evolved?
In the following section, an overview of the literature has been presented to better understand the basis on which this research has been built upon along with the current state of knowledge on this topic. The next section is dedicated to the research strategies that were used as well as the steps that helped in choosing the sample of articles that were best suited for TT analysis. Results and a discussion of the bibliometric analysis are revealed in Section 4, while the final section concludes the main research lines of the study and presents potential future directions.

Tourism and Transformation
Within the context of a gradual shift towards the transformative economy [51] along with the need for change in the world on the road to a more sustainable future, experiences that tend to have transformative outcomes are prone to get an increased importance in the near future [53], and therefore the tourism industry may be the answer to this growing demand, as it has an ace up its sleeve when it comes to selling experiences [54], acting as a tool for inner transformation [39]. The pandemic context has resulted in a number of changes in tourist's desires, with an increase in mindful, responsible and purpose-meaning travellers [55] that shifted from being keen mostly on hedonic pleasures, towards seeking a path concerning more eudaimonic experiences that can transform tourism consumption in meaningful ways [56,57], by creating a space of learning and growth [8], improving healing, wellbeing, re-establishing social bounds, as well as providing an opportunity for making sense of existential dilemmas [55]. TT is not defined by a specific kind of motivation [58], but rather by an increased particularity of one's own reality [1], as tourists embarking on the journey have already set certain expectations based on their experiences, different perceptions and current state of knowledge [1]. There is a continuous loop between tourism and transformation, as the first has a well-known position to guide activities that can change people's lives [3,59] and the latter being seen as an important agent of adaptation and recalibration in the ever-changing nature of tourism [60].
The theoretical basis for many of the research regarding TT is Mezirow's view upon transformative learning. According to the theory, individuals that find themselves at crossroads need to acquire new meaningful perspectives as they can no longer identify with their sense of self. These perspective shifts that could be gained through the dialogue with others, facilitate forming new concepts, values and assumptions by drawing comparisons and reflect upon one's life that could ultimately lead to permanent transformation and positive changes in one's behaviour [11]. Even though initially developed as a new approach to adult learning, it later evolved into a juncture between the theory and tourism [47,48] and began to spread across various tourism contexts, such as cross-cultural [20], volunteer [10], and community-based [26]. These connections were foreseen by Kottler whom also discussed about the same alternative views on life that can ultimately lead to positive changes and personal growth when he first associated the pair of terms" transformative" and" travel" while debating on the transformative travellers' profile, motivations and the effect of travelling as an approach to heal oneself, often resulted from transforming one's perspective on life [12]. Nowadays, widely known as transformative tourism, the literature that sprung from these two pillars of TT research continues to undergo improvements, gain new insights, and proliferate as time goes by.

Transformative Tourism Experience
Often driven by intrinsic motivations of fulfilling one's true potential [61], transformative experiences are different from mundane activities [62], as are considered to be more-than-human, ongoing and incomplete [63], having the ability to lead towards longlasting perceptual and behavioural changes [48,64] that may overall improve the quality of life and wellbeing of the individuals [28]. The process of transformative tourism is described through a series of steps [11,56], usually initiated when a "disorienting dilemma" is triggered, that challenges an individual's way of thinking and makes one self-reflect on their own biases [65]. These stages are linked to Campbell's monomyth (1949) known as the hero's journey [66], where one's dissatisfied with their own mundane life and embarks on a journey where rules and boundaries are unknown, and the traveller is put through a series of tests that trigger the transformation process by seeing and doing unfamiliar things while getting into social contexts with strangers [9]. After the trials are accomplished, the hero returns home with a new outlook on life and, along with the help of those around him, the newly acquired worldview can be passed on and is believed to last over time [9]. Therefore, it happens when one gets out of their comfort zone [12] and has their valuesystem challenged [67], by learning to embrace cross-culturalism, understanding [68] and gaining social empowerment [69] that can ultimately serve as a higher purpose of life [70]. These holotropic experiences [71] of transformative tourism aid towards changing the McDonaldization of the world [72].

Ethos
The mindset of the consumer before embarking on a journey is an aspect to consider when it comes to transformation [1] because as long as the mind is ready and there is openness to change and to acquire new experiences [73], a paratelic state of mind of the consumer is formed [58] where one wants to immerse into the whole experience and thus capitalise on the context conducive to triggering the transformation process. This previously induced state of mind can instigate consumer's transformation for both those who intentionally search for it [12,74,75] or those who initially have other pre-embarking motivations [23,34] that change under different stimuli and contexts. There is a need for a Ricoeurdian 'ipse' mentality in which consumers understand the evolution of identity over time and thus remain open to multiple worldviews [23] as their identity may slowly shift and consolidate after experiencing a transformative trip [76]. The thought with which many consumers embark on a journey relates to different personal circumstances as they begin to question the reality they live in as well as the current state they find themselves in [77]. Such circumstances relate to social, physical, professional, and even existential challenges [33] and usually help the individual to develop critical thinking [78] and see problems from new angles when returning home [79].
Transformative tourists can be seen as independent [80], seeker types [81], motivated by a desire to learn and transform [16] themselves and the world around them [82], having the ability to immerse in the experience and have an open mind towards change [1]. There have been only few studies that researched on demographic aspects of the tourists and therefore this area requires more research [8,83]. Gender-wise, the female process of transformation is marked by soft transformations that include bodily sensations and selfconsciousness while male experience is included in the hard section, being characterised by flow, adaptation, and a sense of community [84]. There is still a need to further research on the socio-demographic aspects of tourists, such as age, gender, and level of education, but also economic status and their relation to TT.

Time
The time provided for activities is also an important variable, as consumers who are not usually constrained by time issues during tourism activities are more open to the process of transformation [58], while on short term trips transformation may fail [85]. However, studies show that this failure is not so much due to a lack of time as to consumers' inability to fully integrate into the context, because even if trips are longer, if done superficially, transformation is less likely to occur [86], concluding that not all experiences always produce transformation [87], yet further research must be conducted to identify new inhibitors towards transformation in matters of the connection between transformative occurrences and time. The degree of significance attributed by a consumer to an experience determines the difference between temporary and long-term transformation [39]. Thus, to reach the point of successful transformations with permanence over time, a certain level of immersion and intentionality is required for the integration and assimilation of the experience to be performed properly [39].

Destination
Another adjunct in transformation relates to the destinations where consumers choose to spend their time, as places and transformative settings become important in reinforcing the meaning of this process for consumers [55]. Some locations stimulate mindsets of openness to new visions, especially in the context of cultural differences, in the form of culture shock [55]. However, transformative tourism destinations do not have to follow a particular pattern for consumers to access these experiences. Radel and Hillman demonstrate this through their research on journeys of non-arrival [88], as even when tourists do not seek a particular destination [88], relying mainly on the journey itself rather than a destination [89], the trip has been shown to be transformative, as it is all based more on how people feel and think about a particular destination and their commitment to experiencing new ways of thinking.
It has long been discovered that nature and interaction with wildlife play an important role in the transformation of the individual [90][91][92][93] as natural environment has the capacity to bring people out of their mundane existence and immerse them into a different world [94], stimulating new emotional effects upon an individual [95].
Travel has the potential to be more effective than therapy for people who need to make changes in their lives [12], becoming an important tool in psychotherapeutic healing [57], with effects induced by therapeutic [96] or feng-shui landscapes [97], or led by the need for healing experiences that positively influence the behavioural intentions for transformation [98]. The quietness, alongside with an atmosphere of a retreat, surrounded by nature, inspired tourists to reach a state in which attitudinal, emotional and physical attributes are being questioned and changed [91]. Anthropogenic places are also transformative, if they can instigate certain emotions and provide authenticity [14], such as retreats that are considered symbols of transformation [81,91], monasteries [99], or even events and festivals [100]. When talking about differences between certain areas ruled by poverty and racial segregation it is noticed that transformation can occur in familiar spaces [31], as well as having the ability to happen even in common places [101]. One of the most valuable aspects of a transformative setting is for it to reach translocality [102] through grasping both a "sense of place" and a "care of place" that aid to providing insights and encourage a sense of responsibility in tourists about a certain destination [103]. Places that embody several senses or fusion of certain elements (people, places, landscapes) are also known to be transformative as they stimulate different meanings to each individual and attribute certain emotions and behaviours that can lead to transformation [1]. Yet, is to be reminded that the more transformative impact a destination has upon a traveller, the more attractive the destination will become in the eyes of the consumer [55]. Therefore, further research on different settings can provide insights on what makes a destination transformative.

Risk, Challenge and Novelty
Transformation is usually accomplished through a series of moments rather than as the entire journey itself [55]. The elements that contribute to these kind of transformative moments are emphasized by the risk and challenge that tend to push peoples boundaries [104][105][106], by novelty and its ability to foster learning [24,74,107] that usually occurs in cross-cultural contexts [108] or by acquiring new skills [109], all of the above contributing to the overall trip satisfaction that is known to have a mediator role in the transformative process [110]. Social inclusivity and acceptance can also foster transformation as it could let the individuals be their true authentic selves in like-minded societies, without fearing of being judged [32,108]. The nature of triggers has yet to be discussed in-depth, and therefore needs further research [111].

Authenticity and Liminality
Authenticity influences transformation to some extent, as its absence can perpetuate various stereotypes and even lead to cultural misunderstandings [112] that subsequently deteriorate the attractiveness of a destination [55], thus discouraging the transformation process [14]. One that is in search for authenticity is lost and desires to escape the mundane life by being aware of their own alienation into the world [113]. The question of staged and real authenticity arises even in matters of places, such as the encounters between wildlife and humans [58]. Therefore, more research must be conducted in this regard. Authenticity, along with liminality, immersiveness, and consumers' own perceptions of their experiences, significantly influence the transformation process. This refers not only to the authenticity of the place where consumers spend their journey, but also as an experience of their own existential authenticity as part of individual transformation [114,115]. Being true to oneself and feeling the freedom to self-express is also connected to liminality [31,115], as it can blur the lines between the mundane and the extraordinary, similar to a temporary fairytale [116] and experience true-to-self emotional changes [117] or unexpected and surprising interactions [58] that aid transformation of the consumer. Inducing liminality must be well mastered and researched furthermore by service providers as too much liminality can bring up confusion and negative effects upon consumers [118,119].

Social Dynamics and Communitas
Transformative tourism is conducted through processes of socialization and acculturation [34,120]. Social interactions can contribute to forming connections with others during tourism activities [1]. These special bonds are often described as communitas [119,121,122], formed connectedness [123], comradery [124], or even family-like relationships [125], and provide mutual exchanges [124] through which the participants can acquire new knowledge, learn new skills, and promote cultural understanding. These can happen in the heat of the moment as of a spontaneous encounter, with people that share same views and beliefs as an ideological bond, or normative by taking different social roles in the new formed communitas [126]. Acculturation happens when consumers arrive in destinations that are contrary to their home life and encounter individuals with other perceptions and beliefs and therefore involuntary starting comparing one to another [1] by engaging in cultural dialogue [127] and start understanding others culture and one's own. But communication goes beyond human bonding, as life-changing transformations are encountered even between humans and different species, promoting mental health and the feeling of connection to natural environments [109]. If consumers are free to experience their transformation without being interrupted by companions that are similar to their home environment such as family or friends that can disrupt the liminal space or lack of access to the lifestyle of residents [22], social dynamic becomes one of the key elements of the transformative experience and therefore the barriers that surround this dimension needs to be further explored.

Emotions and Peak Experiences
Even though Mezirow's theory [11] has been a mainstay in the TT scene, Taylor (1997) pointed out the lack of feelings and emotions in his theory [35], therefore academics have slowly started to introduce the role of emotions in transformation [36][37][38] as tourism, transformation and emotions are closely related [63]. Through cognitive (thoughts and beliefs) and affective (emotional reactions) stimulation to a meaningful experience, consumers transform both themselves and the actions they take [6], therefore being precursors to the transformative power of the experience [128]. Emotions have an educating role in shifting perspectives [38], such as the experience of awe expressed in terms of life-changing events [106] or educating consumers towards pro-environmentally behaviours [129]. Some experiences that have a lot of emotional impact on a consumer can lead to the loss of solidity induced by sentiments of fear, helplessness, anger, and self-reproach [130]. This vulnerability state shifts from a dispositional state into a transformative experience [130]. Emotionally charged moments that can lead to wholeness [131], intense happiness, and fulfilment are called "peak experiences" [132] and can be triggered by spontaneity and novelty, unity with others or with nature, introspection, self-development and aesthetic experiences [74]. Therefore Kirillova attributed new dimensions to the transformation process, comparing them to an extended peak experience that springs from both pleasurable and painful experiences, and that usually occurs spontaneously towards the end of a trip [74], while some argue it could happen anytime during the trip [8] as there is a lack of specific moments in which transformation occurs [22]. Similar to "peak experiences", there are once in a lifetime experiences that alter the ego, mind and body with an intensity experienced during these moments by individuals both physically and emotionally, known as existential hapax [133] that can produce irreversible changes in one's behaviour and worldview. Therefore, further research towards the area of cognition and emotions should be considered [58,69], including bodily feelings and memories that can enrich tourism transformations [133], understand the present and appreciate one's transformation as well as the capacity to lead towards a higher frequency of visits in a particular area [37].

Self-Reflection
Self-reflection [11] is a critical part of the transformative experience [22] as it attributes meaning to a trip [107] which adds longevity to the transformation process [84] or creates the failure of a transformation when tourists do not reflect on what they have experienced [134]. Reflecting on a triggering episode provides tourists clarity with regarding themselves and their experiences, possibly with prolonged transformative effects back home, as they begin reintegrating the experience and wisdom learned into the mundane life [9] and therefore make significant changes [58,135]. This process of reflection can take place both formally, through post-trip discussions with various travellers and family [136] and even journal writing, or informally through keeping contact with locals and travellers that stimulate memories and imagination of the journey, along with various media representations, such as films, documentaries, television programmes, or even magazines [1]. Storytelling has the role of reinforcing the meaning of a transformative experience, thus often being used as a tool in the case of emphasizing the process of reflection [137,138], which is why some service providers take advantage of this fact, as a part of encouraging the circular economy [139] and by inducing reflection through questions and discourse art within transformative rituals [140]. Other reflective processes can be materialised into expressive drawings [69], interviews taken by academics that usually appear at the end of the trip [141], travel blogs [107], and through souvenirs as they offer consumers the opportunity to recreate the tourist experience long after its completion [142].

Tourists' Outcomes
Transformative tourism experiences talk about physical, emotional, attitudinal changes as well as the acquisition of context-specific skills [23,32] or even academic benefits [143], leading people towards change and transcendence to other perspectives [144], thus beginning to develop a new understanding of themselves and those around them [145,146]. As a result of transformative experiences, many participants felt a personal change in attitude and behaviour that would help them cope with everyday challenges [53]. Introduced generically as self-change or life-changing experiences [147][148][149], these transformations are even translated into the film industry, where the main characters go through a rite of passage or hero's journey from which they return changed [150,151]. Some transformation outcomes are difficult to quantify [10] since they possess many variables with no specific cultural, traditional, ethnical, age or gender limitations [39]. As each experience is unique to one's reality, some transformations can be positive and others negative regarding how consumers are addressing the experience [64]. Ergo, researchers should further aim to decipher the yin and yang nature of transformative experiences.

Psychological
Some consumers finally found freedom and empowerment [104], a sense of importance [152] connection to their birthplace [153], while some started trusting themselves and their newly acquired perspectives [16], passed on what they have learned in their community [154], overcame personal fears [155], gained confidence [156], changed their parental philosophy and noticed growth in adaptability [157], or even engaged more in personal growth, all pertained as beneficial aspects acquired from travel [158]. Transformative tourism can encourage towards sustainable behaviours [159] by immersing participants in the environment [94], but also through long-lasting changes in individuals' identities leading to major shifts in priorities and new habits [23]. Most of the time, upon returning home, tourists feel a state of anxiety as they make the transition from liminality back to everyday routine, but with newly acquired perspectives on life [114]. Thus, both consumers and service providers should take these aspects into account and balance the phenomenon in order not to diminish the transformation.

Physical
Other transformations take the form of overcoming personal physical limits [16,123], as understanding or overcoming one's limits is part of transformation [63]. It can be reached through effort or suffering that can even be seen as exciting for some consumers [53], resulting in an increased level of personal resilience [39,53,111], self-esteem, and selfefficacy [16]. There is also a link between consumer's self-esteem and the intention of healing oneself [98], therefore TT outcomes are linked to the health and wellbeing of the individuals. Improvements in appearance [160] or physical abilities [91,161], such as kayaking, fishing, snorkeling, and hiking [94], are also being considered an additional key element of transformative experience [8].

Social
Social dynamics play an important role in developing TT as it can lead to a broadened mindset [68], a blossoming attitude towards society, becoming more tolerant [162], humble [21,163], kind [34], attentive [164], and altruistic towards one's culture, therefore creating intercultural bonds, forming new intercultural competences [16,165] and gaining relational consciousness [166]. Yet, the immersion in local culture must be consented in order to maintain an equilibrium on both sides, as otherwise studies showcase a negative side of social interactions and culture put into play [167]. As these changes benefit both sides of the story, the transformation process is linked to transformations in the resident's society, by getting them to become more respectful and involved in creating experiences for tourists [34,165].

Learning and Mastery
Transformative tourism allows consumers to learn about new environments, cultures and different mindsets that can shift their perspectives and help them acquire new skills, attribute new meanings, and foster a global mindset that can last long after the experience by finally understanding the interconnectedness of everything that surrounds them [168]. In this case of knowledge, some consumers established new routines while some experienced role and career changes, even a willingness to educate others around them with their new discovered knowledge [169], hence bettering their lifestyles [147]. Learning about a culture can be translated in attaining local skills, such as playing traditional games, cooking, fishing, and even learning how to fly kites [170]. Sustaining pro-environmental behaviour is also an outcome of transformative tourism [171], as it can foster environmental awareness [172] and responsibility towards the environment [46], along with learning new skills, such as tree planting [94], an increased attentiveness towards water consumption [169], or such skills that can aid an individual throughout life [146].

Role of Facilitators
Even though consumers play an active role in co-creating their experience [173], facilitators are the ones guiding people throughout their transformation by building the right environment and ambience for the process to begin and get amplified throughout the trip [40]. Through service system transformation [122,174], stakeholders outline different strategies [28], identifying several key elements that are prone to inducing the transformative process and creating special services and products, using core resources and specific design for the experiences [44] that are carefully framed to induce liminality and instigate formation of communitas [140], while eliminating potential factors that can disturb the process such as overly-commercialised transformations [34,121]. Such examples of transformative leadership [45] can be seen in different organisations [29], from site administration that induces several cognitive and affective scenarios [175], to tour guides that are encouraged to stop being conventional and lead consumers throughout their experiences [165,176,177], clients that are being encouraged by service providers to change their habits and constantly adopt new challenges that generate transformative behaviours [96], stakeholders that are emboldened to educate the individuals towards sustainability [172], designed programs to facilitate transformative learning [178] or even the usage of transformative technologies [179], such as AI that can aid the potential to transform existing tourism experiences and unlock a new level of custom-made tourists experiences [180]. This holistic perspective still needs further research as it has only been discussed over the past few years. Yet, there are also cases where some organisations superficially treat transformation more as a form of profit than in a way of helping individuals on different journeys. In such cases, if the intention is not there, consumers will not be able to transform [181], tourists ending up only with marketing proclaims that do not match the reality [55], rehearsing the same old adage of an unrealistically optimistic side of the transformative story. In order to achieve a proper marketing strategy and to match with what was promised [182], both service providers and the community should be aware and informed about the transformative phenomenon, how it happens and what it entails alongside with taking the personalised needs of consumers into account. The reasoning behind it is to avoid unrealistic views of transformation and consequently disappointing tourists and their perception of TT, indirectly influencing their future travel choices. Some proposed an emphasis on symbolism as a benchmark in TT marketing [9], while others considered relating transformation to magic [34] yet maintaining genuineness of the marketing strategy. However, this marketing dimension must be better shaped through research [48] to maintain the same waterline between truth, outcomes, and consumers desires.

Facilitators' Outcomes
But the tourists are not the only ones being transformed [165,183], as transformation is a co-creative phenomenon that requires involvement on both sides and works by exchanging ideas and learn about other cultures [184], knowledge that would benefit locals, visitors, and the environment [124]. In some cases, transformation is more evident in the host communities than in tourist themselves, providing eudaimonic experiences to locals [149], as seeing consumers enjoying and appreciating one's culture [185] enhances its value, making hosts more self-aware and appreciative of their own culture and therefore shaping a host-guest connection for the better [25]. Some service providers, such as tour guides, learn to reflect upon their own values and attitudes that lead to positive changes in their lives [186], while some of the hosts gain an understanding of how to be more environmentally friendly, to take on new responsibilities, switch gender roles and feel empowered by it, and even revitalising culture practices and traditions, being proud of their ability to learn, exchange, teach cultural practices, and form communitas with visitors [26]. However, further research on this topic is required as it has only permeated the academic scene in recent years. Figure 1 summarizes the findings of the literature review section of the article. Closely tied with positive psychology that is known to contribute to one's healthy lifestyle, once committed, the transformative experience has the potential to plant the seeds for future series of lasting transformations [187], as the consumer recognizes the positive changes in their life related to this process, making them eager to further explore this area of life-changing experiences that could improve the wellbeing and overall quality of life of the individuals [28]. Therefore, it is necessary for service providers to religiously research these experiences, as they take the role of catalysts for a chain of transformations not only in the consumer's life, but in the lives of all actors participating in this tourism phenomenon. From an inductive point of view, a transformed customer is going to enhance local communities' perceptions by increasing uniqueness of individuals and overall awareness (e.g., social, environmental), by adding valuable information for service providers to outline TT dimensions, but also transform their home community by showcasing, promoting and educating individuals on new behaviours once they arrive back from the trip. These outcomes can enhance sustainable and pro-environmental behaviours [8] through pro-active transformative learning and increased self-awareness [94] that can elongate the protection over one's environment and culture. Furthermore, engaging with new people and environments with their now-changed worldview, a transformed customer contributes to subsequent transformative echoes throughout one's lifetime. Considering the previous chain of events, it, can be considered that transformative tourism has indeed the potential of changing the world.
This section aims to deliver a comprehensive view upon the subject and to extract dimensions that still need to be discussed or yet to be more carefully analysed. Further research requires longitudinal studies [8,188], adding new depths of time [178] and changes along with a consistent cultural background [22], as well as filling the gaps with other types of tourism that engage in the transformation process [111]. There is also a requirement of a more detailed view upon tourists' profiles [8], and the different nature of triggers such as liminality, cognition, emotion, and authenticity along with the insertion of new settings through transformative perspective lens. Therefore, a requirement of layering information for a better organisation and explication of TT dimensions is to be considered, along with holistic perspectives upon the transformation process, new methods and paradigms that could be employed [49], and an accurate portrayal of all the actors involved in the transformative process. Furthermore, given that this process is gaining momentum and is constantly developing, there is a need for a bibliometric approach to track its growth in a more objective and quantitative manner.

Data Collection and Article Screening
The investigation reviewed papers associated with transformative tourism found on four databases (Web of Science, Science Direct, EBSCO Discovery Service-EDC and Google Scholar). The reason for choosing several databases was to encompass a larger area of research and increase the accuracy of the study. Publication selection phase followed Moher et al. (2009)'s Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), resulting in a four-step process including identification of studies, screening, eligibility and inclusion [189], as can be observed in Figure 2. During the identification phase, several sets of combined keywords were applied to collect research related to transformative tourism. Terms such as "transformation", "transformative", "travel", "tourism", and "experience" were used to identify a broader spectrum of the subject, as individually, they were the most encountered keywords utilised within the TT domain, found after a brief scan over the four databases. Namely, "transformative tourism or travel" as well as "transformative experience(s)" and "tourism or travel" and "transformation" were used during the search phase. In the screening process, publication types other than English-only journal articles were excluded, except for a few bilingual papers. Decisions to employ journal articles were only based on the reasoning of being a source of certified and critically reviewed papers [190] along with the preference on journals among researchers regarding bibliometric analysis [191]. Several papers (n = 123) could not be further found on the platforms due to technical issues regarding the redirection to a temporarily unavailable server and therefore were included in a not available section (N/A). In the eligibility phase, even though findings resulted in an enormous number of publications, all of them were scrutinized by titles, abstracts and keywords. To prevent the omission of an important body of knowledge, another analysis on articles that were not initially suitable for the study was conducted. Content-wise, a large number of papers were found to be unrelated to travel and tourism and therefore have been eliminated. Publications that failed to acknowledge the process of transformative tourism or linkages of both tourism and transformation were also excluded. Fair few articles, even if in alignment with ideas related to TT, such as the power of awe [192], authenticity [193], storytelling [194], immersion [195], as well as memorable experience and subjective wellbeing [196], were considered ineffectual to the present study as they were unable to produce connections to TT and therefore excluded. The last criterion of exclusion was time, as database research concluded on 1 May 2022, publications released after this date were excluded from this study. The time frame analysed was based on the earliest [12] and latest [42] articles related to TT found on the databases, resulting in a research period of twenty-five years. Prior to removing duplicates, data regarding citation count were saved as it can measure the overall quality of work [197].
From initially 7029 entries, during the PRISMA process of selection 250 articles were found eligible and included in the study, consisting of literature that has been discussed back-and-forth by researchers in the field, papers emphasizing junctures between transformation, tourism and other domains, as well as newly introduced publications on transformative tourism that incorporate previous TT studies. The bibliometric aspects from all the databases were merged and exported into an Excel spreadsheet for analysis. The data extracted included article title, abstract, keywords, authors and their affiliations, publication date, journal titles and categories, publishers, institutions, funding associations, geographical distribution, and citation count. The main topics and themes of the papers were also added to another Excel spreadsheet for further qualitative analysis.

Data Analysis
To fulfil the scope of this study, a bibliometric analysis was employed as it can reveal certain features of science, including most contributing authors, universities, countries, journals, and institutions [198], regarding a certain area of research and observe the evolution of the scientific literature of the related knowledge domain. This type of analysis is paramount to studying literature tendencies and the state of art across various fields [199] and therefore able to manage a significant volume of scientific data and produce noteworthy overall impact [200]. The central approach of the analysis was based on Donthu et al.'s (2021) main techniques of performance, science mapping and enrichment analysis [200]. Performance is related to both publication and citation metrics, whereas science mapping focuses mainly on the relationship among publications, topics, and authors, while enrichment is characterised by network analysis, clustering, and visualisation techniques [200]. Yet, since scientometrics evaluates the quantitative aspects of science it imbricates bibliometric analysis to a degree [201] and was therefore added in the methodology of the study. Combined, both techniques provide a comprehensive view on productivity, impact and influence on the subject in matter.
The annual number of publications determined publishing tendencies, while the geographical distribution of the articles aided in identifying the level of dissemination in TT research. The overall quality of work was measured using citation analysis on publications and authors, identifying the most impactful papers as well as most influential authors. Co-authorship was analysed in order to observe collaboration patterns between universities or authors, to better understand ongoing friendly literature debates, as well as the spread of the subject both nationally and internationally. The level of reliance and relevance regarding the sources of information was analysed using parameters such as quartile, h-index, impact factor, and citation indicator on journals and publishers in TT. Further observation of the interdisciplinarity of the TT was revealed by the subjects and categories of the journals in which the articles were published. The most influential and specialised universities were discovered alongside the funding associations that supported the research in this area of study. The evolution of the intellectual structure as well as the emerging trends of transformative tourism were identified using the most occurred keywords to capture the development of TT overtime as well as the level of propagation and capacity of encompassing new information along the way. In order to obtain the broadest possible perspective on the subject, both main and sub theme articles on TT were considered, as to discover new junctures in topics and also to observe changes in the focus on the TT literature. In addition, the main research methods, perspectives and types of tourism regarding TT were displayed to add further dimension to the subject in matter.
Performance analysis technique parameters were manually searched and included total publications (TP), number of contributing authors (NCA), sole-authored publications (SA), co-authored publications (CA), total citations (CT), and h-index (h). Correlation between performance parameters resulted in the science mapping technique that consisted of citation, co-occurrence and co-authorship analysis. Data regarding geographic distribution, universities, and funding associations were extracted from a quick scan over whole documents. Journal rankings, subjects, and categories were identified using SCImago Database while Journal Impact Factor and Journal Citation Indicator were found on Clarivate's Journal Citations Reports. Information from all the databases were merged using Mendeley reference manager and imported into VOSviewer software for further usage of bibliometric tools and visualisation techniques. By a thorough examination, qualitative dimensions were extracted as follows: (1) main topics were clustered and transposed into literature review section; (2) types of tourism were listed and shifted afterwards into bigger categories (e.g., cultural tourism comprises dark, film, aboriginal tourism etc.); (3) methods applied were classified into qualitative, quantitative and mixed categories after extracting them from methodology section; while (4) perspective parameters were grouped based on whether the publications were aimed towards tourists, stakeholders, hosts or having an overall view of the subject in matter. All the aforementioned analyses aimed to obtain an up-to-date comprehensive overview of the nature of TT.

Results and Discussion
Throughout the following section, the results obtained from the bibliometric analysis were displayed and discussed. These objective parameters served as a means to better frame the evolution of TT literature and finding the amount of interest granted to this matter, such as the degree of information dissemination, overall quality of work, stand-out publications, most reliable sources of information, collaboration patterns, level of interdisciplinarity and expertise, emerging trends, as well as most used methods, perspectives, and types of tourism that shape TT.

General Literature Trends of Transformative Tourism Related Publications
Connections between tourism and transformation were long acknowledged by researchers [4], yet it was the year of 1998 when Kottler first introduced the term of "transformative travel" [12]. What was believed to be a hesitant start (1998)(1999)(2000)(2001)(2002)(2003), with intertwined ups and downs along the years, resulted in an overall positive tendency in growth and interest according to the trendline of literature on TT (Figure 3). In the last few years (2017-2022), more than 70% of the whole literature has been written, therefore confirming Pine and Gilmore's (2013) statement of TT growing into an emerging trend in the industry [51], along with its transformative experiences becoming the new buzzword [6]. The surge of interest in TT literature in the year of 2020 was reasoned by the significant change in world-wide consciousness under the circumstances of COVID-19 pandemic as its impact hurtled into a more transformative form of tourism [202] by introducing new perspectives from different domains into the research design [203] that could aid both economic and social recovery [39] and that could also lead to spiritual elevation and healing [57]. The year of 2022 presented a lower number of articles as it was measured only by the first five months of the year, since the analysis conducted ended in May 2022.

Geographic Distribution
As a matter of geographic distribution, articles regarding TT were found to be conducted in several regions (Table 1). To have a better understanding of the outspread this phenomenon possesses, data were measured based on countries of affiliation. Since various papers had more than one author, several countries were attributed to a single article, but duplicates found in the same article were removed for a better picture on the subject. Table 1. Geographic distribution of publications on TT.

Europe 121
United Kingdom (40) The highest frequency was attributed to Europe, which was found in 121 articles, followed by North America (84), Oceania (61), and Asia and Pacific (33) ending with Africa (10), Middle East (6), and South America (6). From a regional point of view, research related to TT was mostly found in Europe, North America, and Oceania, whereas countrywise, United Kingdom (40), United States (73), and Australia (49) were found to be the most prolific countries regarding the number of articles on transformative tourism. There were 48 countries that have published at least one paper related to the topic, 15 countries with more than five papers and eight countries with more than 10 articles regarding TT. There is a visible difference in the ratio of developed and emerging countries, the first dominating the latter, as most partnerships are found to be only between developed countries, overlooking potentially valuable information on TT development from not associating with other emerging countries. Even if the numbers are uneven, it can be stated that the interest of this phenomenon is becoming world-wide, having a high degree of information dissemination.

Citation Analysis
After acknowledging the growth in the number of papers related to TT over the years, as well as the wide geographic distribution of the articles, the next step considered concerned the level of relevance of the papers. Thus, the number of citations was analysed as it can measure the influence of both the authors and journals in the matter [204], as well as the overall quality of literature [197]. The information regarding the citation count was gathered from the four databases analysed in the study (Web of Science, EBSCO, Science Direct and Google Scholar).
A general view of the citation structure in TT was represented in Table 2. It was discerned that the literature on transformative tourism consisted of a scant number of articles in charge of a high volume of citations that varies from 200 up to over 500 citations. The familiarity and accesibility of Google Scholar database are shown both in the number of total citations (59.2% of overall citations) as well as being the host of the most cited papers on TT of all the databases. Close after, WOS database encountered fair few top cited articles as well as a large number of total citations on TT (21.8% of overall citations). Both EBSCO and SD databases, even if owning the smallest amount of TT literature, represented between almost 6% and respectively 13.09% of overall citations. In spite of the differences in the citation patterns from one database to another, the majority of articles range from one to 100 citations per database, therefore outlining the equal interest granted among the databases as well as the novelty of the subject in matter. At the other end of the line, a notable number of articles could not hit the 1 citation level as most of the articles situated between these measurements were recently added in the academic scene and have had no time to be cited by other scholars yet. Nevertheless, reckoning up the average citation count regarding TT as well as the continual growth shown in the recent years, an increase in citations in the near future is to be expected.
The identification of the most impactful publications was measured considering the the top five publications on each database in number of citations as well as the average of their citations per year (C/Y). As represented in Table 3, Sigala's work from 2020 occupied the first position in three out of four databases, with an impressive number of citations obtained in the shortest amount of time. An explanation for this position was the high level of interdisciplinarity (coupled with business and health matters), as well as its linkage to the pandemic (COVID-19), overall considering transformation to be a focal point in tourism nowadays [203]. Minor differences between three out of four databases were found, resulting in a consensus in regard to the most impactful publications. Whether following the narrative of transformation in backpacking tourism [14], describing tourism as a potential agent of change [30], revealing the capacity of international sojourns to transform students' personal and professional lives [16], pinpointing the transformative learning process through travel and tourism [205] and associating it with alternative ways of sustainable tourism [206], or even showcasing the transformative benefits in wellness [24], spirituality [77], volunteering [207], or extreme sports tourism [13,18], the top publications enabled the reader to discover different facets of transformation in tourism as well as the importance of including such aspects into the day-to-day life. Most of the publications encountered in the list (Table 3) have had a long history of activity (from eight up to 23 years), and therefore present a significant time span to be analysed, reviewed, and cited.  Out of a total of 20,129 citations on transformative tourism literature on the four databases, 8261 citations were found in the first 12 most cited papers (41.04%). Thus, these articles were considered fundamental works on the subject in matter.
The most influential authors on TT were pinpointed using total number of publications regarding transformative tourism along with the corresponding number of citations, all represented in Table 4. The authors with at least three publications that managed to achieve at least a h-index of 3 in one of the four databases were added to the list, resulting in a total of twelve authors. In this scenario, Lehto was positioned first on the list of authors, with a total of five publications on the subject, 816 total citations and the highest h-index of all (five), confirming that the author in discuss had the greatest impact regarding transformative tourism literature. The antithesis between authors was also highlighted, whereas even if some authors met the same criteria of the number of publications, the difference between the citation count was visible (e.g., Sigala with a total of 2322 citations and Soulard with 149 citations). Regarding country-of-origin frequency, United States led the way with four entries, half belonging to Purdue University and the other half to Virginia Tech University.

Co-Authorship
According to the TT literature, various authors contributed along the way to the development of this field of study, resulting in 509 authors who published articles related to transformative tourism in a time span of twenty-four years (1998 to 2022). From a total of 509 authors, only 78 had sole-author publications, resulting in a myriad of two or more authors on a single publication (84.67%). Additionally, several articles were found to be co-authored by the same scholars, therefore resulting in a high collaboration level on the subject (Table 5). Co-authorship was examined to highlight the level of interactions between researchers under the form of intellectual relationships [208]. Several articles were co-authored internationally (e.g., USA-Hong Kong; Italy-New Zealand-South Africa), some nationally (e.g., Soulard  Most of the repetitive collaboration patterns were observed between 2014 and 2020 (Figure 4), concluding in a worldwide increase in the interest rate reinforced by the expansion of literature findings. In addition, these co-authorships could outline and integrate different points of view and contribute to an increased level of coherence and conceiving core characteristics that may help and encourage scholars globally. Continuous collaborations between formed groups of researchers could signify the need of more in-depth observations in the nature of TT, as more fruitful directions worth of being highlighted are discovered after conducting initial research, with researchers thus slowly becoming specialised in the subject. Yet, more collaborations should be established in order to form a solid network focused on TT.

Journal and Publisher Analysis
A total of 101 journals were found to have published articles related to transformative tourism (Table 6). From the total, a noteworthy percentage (26%) of journals published only one single article, implying the fact that the theme could be transposed into several other domains, strengthening the idea of a high level of interdisciplinarity regarding TT (e.g., subjects as psychology, sustainability and ethnography). Next in line were the journals that have published two (11.2%), three (1.2%), or four articles (8%) alongside the vast majority that have published between five and twenty-six articles per journal (53.6%), indicating that most journals were specialised and tourism related.
The most prolific journals were computed using number of publications and top citations regarding transformative tourism. The set of data was complemented by journal ranking (quartile; Q) and h-index. The final list (Table 6) included many reliable tourism and hospitality journals, the majority of which were situated in the first quartile as found on SCIMago Database. Clarivate's Journal Citations Reports helped identifying the Journal Impact Factor (JIF) for the year of 2020 and Journal Citation Indicator (JCI) over the last three years. According to Clarivate, the usual value of JCI is 1, and therefore articles that had a JCI of more than 1 were considered as having a greater citation impact than the average.  In this research, 12 journals from the top list on TT had a value that surpassed the average, even with a score of 2.99 in the case of Journal of Travel Research. Journal Impact Factor on top journals ranged from 1762 to 10982, the top three with biggest JFI being positioned in top ten of journals on TT. Two of the top journals could not be found in the system while some (n = 3) had data only on JCI indicating some did not meet the metrics for Journal Impact Factor to be calculated.
Annals of Tourism Research was found to be the leader of the list, with 10.4% of the total of articles on TT, 5828 total citations and a h-index of 21 on the TT literature, seconded by Tourism Management Perspectives with only half of the articles on the subject (5.2%), far fewer citations (1176), and a h-index of 9, whereas the third Journal of Sustainable Tourism was situated as being 4.4% of the total articles on transformative tourism, with 1202 citations and the same h-index as the previous journal (9). The top three journals were also scored Q1 in the Tourism, Leisure and Hospitality Management category and having a total journal h-index situated between 54 and 187. As for the top five publishers, Taylor and Francis Ltd. led the way with 15 articles published on TT, closely followed by Routledge (14), Elsevier (10), Sage (eight), and Wiley-Blackwell (five). For this analysis, journals that were not to be found in the SCImago Database were excluded from the list (n = 21). The top 20 journals have published 154 articles, representing 61.6% of the total number of publications on the subject. Citation-wise, the first 20 most prolific journals covered 76.97% of all citations on TT (15,494 citations out of a total number of 20129) and were therefore considered to be specialised on the subject.
A representation of the evolution of the annual number of papers published in top 20 journals was displayed in Table 7, with a clear distinction of continuous interest growth over the years. Findings show that in the first few years up until 2012, a very small number of journals published articles on this topic, while the latter years show an evolution in matters of interest in TT. While some journals maintained a consistent pace, by publishing articles almost every year (e.g., Annals of Tourism Research), some gained interest and joined along the way, as more and more linkages were discovered between TT and other subject areas (e.g., Sustainability, Religions, Journal of Business Research).   Tourism Research  1  1  1  1  3  3  2  3  1  5  3  2  26  Tourism Management  Perspectives  5  3  2  2  1  13 Journal Articles regarding transformative tourism were found in twelve different journal subjects. The most encountered were situated around Social Sciences (36%), Business, Management and Accounting (30.9%), and Arts and Humanities (8.8%), yet an array of journal subjects touched upon transformative tourism such as Environmental Science, Psychology, Earth and Planetary Sciences, Medicine, Computer Science, and even Engineering. Each journal subject related to TT had several categories (n = 56), the most prominent being related to tourism and geography, such as Tourism, Leisure and Hospitality Management (21.2%) and Geography, Planning and Development (14.1%). Not that prominent yet noticeable categories included Social and Political Science (4.9%), Cultural Studies (4.3%), Education (3.3%), Social Psychology (3.3%), and Management, Monitoring, Policy and Law (3.3%). These findings revealed the variety of topics that transformative tourism could address (Table 8).

Universities and Funding Associations
Research has shown that 265 different universities and institutions have contributed to the body of knowledge regarding transformative tourism from all over the world. More than 70% of universities (n = 194) contributed to only one article, 12.07% of them to two articles (n = 32), while 7.1% of them contributed to three articles (n = 19). A representation of the top universities among TT articles was designed in Table 9, based on the number of articles written and their reference times as some articles had one or more authors from the same institutions. The criteria for the top 20 was for the universities to have at least one entry in four or more articles, representing a total of only 7.54% of all universities.  Findings shown that Griffith University received first place regarding both the number of articles in which it contributed (n = 10) and as the most encountered university among TT publications (n = 15), denoting its interest in the subject among scholars. Out of a of 265 universities, only eight contributed to more than five articles. The reason behind these results was given by the novelty of the subject and its interdisciplinarity, which is still changing shape and adding value as time goes by and therefore many institutions still have time to create new links and become specialised in the field of study. What is certain is that with this evolutionary path and the discovery of various themes that could be included in this area of study, more and more institutions will soon start to gravitate towards all that transformative tourism has yet to offer.
Considering that this subject has developed relatively recent in the academic world, the number of associations providing funds is small, consisting of 21.2% (Table 10) out of the total articles. Thus, it is to be specified that the number of articles that were integrated in the "Not funded" category (78.8%) also included the publications in which the authors not clearly mentioned the support offered by certain institutions, and therefore added to the latter section. However, the typology of funding associations seemed to be quite varied, ranging from governmental support, to research councils, certain awards, national funds to grants offered by universities and even private actors, reflecting the increased and diverse interest on the subject in matter. Out of all 53 articles funded, five were sponsored by Portuguese National Funding Agency for Science, Research and Technology (FCT) and four entries were attributed to Yale and its branches, while eight funding associations had two entries each, leaving the rest (n = 28) with only one entry each.

Intellectual Structure and Emerging Trends
In the following section, the most common words and group of words encountered in titles and abstracts of the articles were taken into consideration to evaluate the most frequently occurring topics in the field using tools provided by VOSviewer. In this research, 5451 terms were identified. Only 362 words or group of words occurred more than five times (6.64%), 151 more than ten times (2.77%), 26 more than 30 times (0.47%), and only 11 more than 50 times (0.20%). The keywords that occurred more than ten times were displayed in Figure 5. Out of 151 terms, a filter of relevance was applied by VOSviewer that selected 60% of the most relevant words, remaining with only ninety-two keywords. Terms that were usually encountered as part of the usual structure of an article, such as "further research" or "area" did not provide information on the specific subject and therefore were excluded, leaving a total of 72 keywords with more than ten occurrences remaining. The size of the nodes represented the number of occurrences of a mentioned keyword, while the size of the lines expressed the number of links between the keywords. TLS (total link strength) indicated the number of links between a word with other words or group of words, embossing the importance of a keyword [209]. The further the nodes from the centre, the fewer links to other keywords were found [209]. The evolution through time was shown by the colour of the nodes and lines. Recently, "COVID" appeared among the keywords in the database, as it shifted the perception of consumers towards a more sustainable way of thinking and acting, this change being echoed in tourism as well. Newer terms, such as "host" and "resident", show the interest towards a more holistic view over the subject in matter, while the usage of combinations consisting of "transformative", "tourism" and its linkages with "experiences", denoted scholars beginning to embrace the terminology among the academic community. The top keywords based on occurrences and TLS were displayed in Table 11. As shown, the five most recurrent words were: travel, outcome, nature, motivation and dimension. The first word defined the action itself, whereas terms, such as outcome, motivation, and dimension, conveyed the interest in the characteristics of transformative tourism, while nature described both the need of understanding the nature of the subject as well as describing one of the preferred settings in which TT takes place.

Theme Identifiers Analysis
Out of 250 articles, just over half of them (51.6%) had transformative tourism as the main topic of debate, discussion and research while 48.4% included transformative tourism only as a part or dimension of other main topics discussed. The reason why the latter were also chosen in the study is that they too contribute to the body of knowledge on transformative tourism by bringing new views and junctions of situations with other research areas which can also be interpreted as a consequence of the interdisciplinarity of the topic in question. Even though in the years of 2017 or 2018, the secondary theme articles were greater in number as the subject was and still is in its discovery phase, in the last few years (2019-2022) it shifted towards articles that expressed TT as the main theme and therefore implying the growth and interest on a more detailed side of the subject. Main theme articles included research that focused only on the transformative process of tourism, whereas articles classified as having secondary topics related to the transformation process in tourism, met one of the following criteria: (a) the transformation process in tourism was highlighted as one of the outcomes or motivations of the main topic that was not initially thought to be related to transformative tourism; (b) the transformation process in tourism was mentioned or joined to other topics discussed in the article, thus forming connections with other domains. Some of the sub-theme articles included the importance of self-love in tourism as an emotion that could lead to more meaningful and transformative experiences [37], or the linkages to hopeful and social tourism [210][211][212][213], the hero's journey as a tool for advertising transformative experiences [214], transformation as a path towards innovation in tourism [215], the transformative potential of the existential wish to search or manifest a person's values and identity [216], or even an exhaustive research on experiences where there was a light shed on transformative experiences [128]. The current state of balance in topic coverage in TT articles is represented below (Table 12), however, a turnaround is expected in the upcoming years as the focus shifts in the favour of more in-depth analyses on the nature of TT, thus enhancing the main theme literature. The distribution of methods within articles based on transformative tourism was shown in Table 13. It was observed that there is a dominance of qualitative analysis, represented by 80.8% of the total methods. Out of 202 articles based only on qualitative analysis, some were purely based on secondary data (n = 68), some on multiple qualitative analysis, such as participatory observation, photography, interviews (n = 62), while some emphasized only on interviews (n = 40) or other forms such as focus groups, narrative or performance inquiries and netnographies (n = 32). New creative means of research such as the use of performance inquiries through drawings [69] or digital environment research using netnographies that conduct various internet analyses [45] were deployed to discover different paths of obtaining qualitative data regarding TT. The preference towards a qualitative approach lies within its capabilities to understand specific relations, concepts and opinions of a given situation which becomes suitable in studying the contextual nature of the transformative experiences as it creates space for revealing in-depth details by observing underlying reasons, motivations and unique perspectives of each and every person experiencing TT. On the other hand, quantitative analysis was significantly lower encountered in only twenty-four articles (9.6%). These methods included both surveys and questionnaires and were mostly utilised for testing several hypotheses on TT such as the Transformative Travel Experience Scale [43] or finding certain descriptive characteristics of tourists' profiles [110]. Mixed methods combined both quantitative and qualitative analyses bringing a far more holistic approach to the subject (9.6%). By considering the methods utilised for mixed analyses, most used qualitative methods were interviews (43.2%) referenced in 108 articles, followed by secondary data (36.8%) in 92 articles and participatory observations (21.2%) in 53 articles, while the quantitative inquiries were surveys (11.2%) encountered in 28 articles and questionnaires (5.2%) in 13 articles. Overall, the ground gained by the qualitative analysis in this case was due to the subjective nature of the transformative experience and the attempt to highlight and bring out many new dimensions to find new connections and add value to more comprehensive frameworks that through usage of quantitative methods could bring renewed promise regarding the practicability of TT. In Table 13 shown above, the research perspectives regarding transformative tourism were also analysed. The vast majority occupied the tourist's point of view (66%), followed by a general approach (17.6%) in which the perspectives were not the main focus of the articles and mostly being analysed through expert lenses. Stakeholders' perspective included organisations and service-providers and reached 5.6% of the articles, while host perspectives only 2.4%. The multiple approach included combined perspectives between the actors towards a more holistic viewpoint and occupied 8.4% of the total articles.
Several types of tourism that are currently represented by TT were found in the research sample, resulting in a number of 9 broad categories as shown below (Table 14).  (5); Aboriginal tourism (1); Dark tourism (7); Temple stays (1); Rural (1); Festival and events (13)-sport events (2); Creative (2); Flamenco tourism (1); Film tourism (2); Food and wine tourism (1); Food-only tourism (1); Slum tourism (1). 39 15 . Most of the articles belonged to a general view (25.6%) upon the subject, either encompassing a range of types of tourism or discussing issues related to other dimensions of this area of study, such as transformative strategies used in organisations [42], intense forms of transformation such as existential hapax [133], a scale to measure transformative travel experiences [43], the role of a transformative tourism destination [155], or even the linkage between TT and positive psychology [297], as it can improve the overall quality of life.
Eight more clusters were identified with cultural tourism occupying 15.6% of total articles, nature-based tourism with 14% of the total articles, religious tourism 11.6%, educational 8.8%, voluntourism 6%, wellness and wellbeing 5.2%. The last two clusters included other types of tourism that could not be integrated into the other sections such as business tourism, mass tourism and smart tourism (7.6%) and niche tourism such as orphanage tourism, paranormal tourism and beer tourism (5.6%). What has been extracted from this analysis is that transformative tourism is increasingly starting to fold into different types of tourism, becoming a desirable outcome especially in recent years with the pandemic and the increasing autonomy and desires of today's generations.

Conclusions and Directions for Further Research
The importance of this study lies within the addition of a new layer to transformative tourism, complementary to what has been written so far in the academic literature by using a bibliometric analysis to capture the evolution in a quantitative and objective manner and therefore enhance the understanding of this phenomenon. The article conducted a bibliometric and visualisation analysis on transformative tourism over a period of twentyfour years (1998-2022) so as to cover the entire period of publication on this topic found on four different databases, thus building an up to date and complete overview of the TT literature.
After a brief content analysis of the 250 publications found on the subject, it can be argued that transformative tourism is gaining interest through the chronology of topics covered, increasing the level of immersion into the subject and highlighting constant movement from theory to practicality. Continuously shape-shifting from one article to the next, the authors actively engage by trying to find solutions to unfinished ideas or problems previously mentioned by other academics, or even bringing new directions into the discussion, the literature thus flourishing and gaining momentum. Several useful literature insights have been provided by researchers over time related to this phenomenon. What can be inferred from the literature review is the capacity of transformation to thrive in both negative and positive emotions to a certain degree, attributing a yin-yang nature to TT. Furthermore, as the course of transformative tourism experience can differ from an individual to the other, the anatomy of TT becomes chameleonic, as a multitude of variables and stimuli (catalysers) can come into shape which subsequently leads to transformation. These contexts are not generally defined by time and space, but by the ethos of all the participants involved in the process, thus highlighting the essential role of co-creation in TT, as newer studies have shown the importance of TT leadership, host communities and consumers working all together towards a greater good, bettering the selves and the world around them, improving overall quality of life and wellbeing. Yet, these variables and catalysers need to be taken into further consideration as they could surface new ideas and provide new developments regarding the subject in matter. Even though academic community is responsive in matters of transformative tourism, literature on the subject still implies a need for more in-depth analysis on certain core components, newly introduced aspects, or even conceptualising different frameworks and their projection through time. Therefore, TT is yet to be fully discovered as many opportunities arise from evaluation and continuity where others left the research stage.
Furthermore, the study examined various aspects of objective matter in understanding TT, finding several key points that serve as a glimpse of evolution on the subject. Although initially the course of the academic literature on TT has been a meandering one with both ups and downs over the past twenty-four years, publications within this area have had an overall positive trend in growth of interest, particularly in the last five years which encompassed over 70% of all literature written on the subject. This sudden surge of interest was coupled with significant changes in worldwide consciousness in the context of the pandemic, but also as new interactions formed between different domains trying to balance out and adapt to current situations.
Transformative tourism literature has been treated as an important research topic as articles were found to be conducted in several world regions such as Europe, North America and Oceania that are currently taking the lead in this matter. Even though unevenly distributed throughout the world, with most articles around United Kingdom, The United States, and Australia, it can be stated that the interest of this phenomenon is worldwide as an emergence of other countries in recent years is also noticeable, therefore emphasizing the continuous outspread of the phenomenon.
Despite having a scant number of articles among a high volume of citations that could be considered reference studies in the field, most of the publications have been only recently added in the academic scene, and therefore are yet to be cited. Most impactful publications have a long history of activity, thus a significant timeframe to be analysed, reviewed and further cited alongside with a high level of cross-disciplinarity and the consideration of transformative tourism as a cure for global problems such as the after-effects induced by COVID-19 or even climate change, that started concerning researchers not only from the tourism field. Its significance in quality of work is blooming as a yearly increase of citations is shown in TT domain, with the expectance of continuity over the next years.
In twenty-four years, a great number of authors participated in the academic research in regard to transformative tourism, yet the greatest impact in literature was achieved by few standout authors from different countries of origin, deducing the fact that several researchers are starting to become specialised in the TT domain. Vast majority of publications contained two or more authors that intertwined internationally, nationally or even belonging to the same universities. Several were co-authored by the same scholars and therefore a high intellectual collaboration level can be deduced from this statement. The repetitive collaboration patterns were observed between 2014 and 2020, concluding in a worldwide increase in interest rates reinforced by the expansion of literature findings and co-creation by bringing new visions to the table. Co-authorship could define and encompass different points of view as well as an accumulation of cohesive core structures that could be applied globally, therefore encouraging growth of literature on this subject.
A noteworthy number of journals were transposed into several domains, therefore strengthening the idea of interdisciplinarity among academic literature on TT. Most prolific journals which comprised the top publications and citations were considered reliable, wellknown and established sources of information that specialised on the subject, and while some present a gradual distribution of growth over time, some gained interest along the way as more linkages were discovered between transformative tourism and other subject areas, therefore sustaining an array of categories that it could address.
Numerous universities and institutions have contributed to the knowledge of TT from all over the world. While some were to be considered specialised as having several articles written on the topic, the majority provided only one article related to TT, thus reinforcing the novelty of the subject, the interdisciplinarity and the ever-changing shape and added value as time goes by that can lead to new joints and discoveries, hence new scholars from different universities would soon come into play and get a grip on the subject.
A small number of funding associations were found in the academic research on TT as it developed relatively recently, yet the actors that contributed were typologically varied and therefore shown a diverse increase in interest. Although few associations have supported research in this area, some have made it a habit (e.g., Portuguese National Funding Agency for Science, Research and Technology (FCT) and Yale and its branches), reinforcing and encouraging the idea of TT development.
The most frequently occurring topics revolved around key characteristics of TT that needed to be examined such as outcomes, motivations, dimensions, nature and the journey itself. Evolution of keywords showed that throughout the years, what started as a form of learning with overall life-changing experiences, has grown into finally associating and embracing the terminology of TT in the academic world, towards greater engagement in a more holistic and sustainable approach, having linkages even to the circular economy, adapting it to today's problems and desires (such as COVID and attaining certain environmental behaviours), including several strategies implemented by organisations and businesses, thus making an overall relevant impact in the world. Further research should dive deeper into the connections with sustainability and circular economy. Even if in terms of the representativeness of the topic there is a balance between transformative tourism as a main or as a secondary theme, it is noticeable that since 2019 there is an emphasis and a shift towards a far more detailed view on TT as studies started embracing the domain more thoroughly.
The dominance of qualitative analysis throughout the years comes in response to the subjective nature of the transformative tourism experiences and by the initial frenzy of discovering as much as possible about the dimensions and connections of this type of tourism, thus gradually adding value to more comprehensive views upon the subject (as new creative methods reinforced along the way), that with the aid of quantitative methods could incorporate, quantify, simplify, and apply new frameworks into a discussion that could be further used to add consensus and eliminate all inconsistencies, which could further support blueprints for practitioners from all over the world. Perspective-wise, mainly focused on tourists' point of view, more research should emphasize the role of co-creation in transformative tourism experiences, including all actors participating in this process and therefore adding a holistic dimension to TT. The root of transformative tourism is forging new connections and it is continually starting to fold into different types of tourism, becoming a desirable outcome especially in recent years due to the pandemic, increase in autonomy, and matching desires of today's generation. Researchers should further examine different destinations, types of tourists and tourism, as well as proper marketing techniques to manage creating a cohesive framework on TT that could be easily followed by other academics and practitioners. By providing empirical evidence of the results of the implementation of TT in different settings, practitioners could further resonate and identify with certain aspects that could be fruitful in their case scenarios, thus providing impetus to try TT. Furthermore, with the acquired information, tourism organisations could also dispense training programs for host communities and tourism facilitators on transformative leadership as well as raising awareness on the impact and benefits of creating transformative experiences, that could be later expressed into local or regional tourism focus groups including all the actors that participate into the TT process, therefore spreading the knowledge of transformative tourism. The more facilitators decide to engage into TT, the more content to be observed by researchers will become available, more partnerships between developed and developing countries could be formed, ultimately ensuring an increase in the level of comprehension, accessibility and visibility of TT on the worldwide tourism scene.
These findings showcase useful information for scholars in this field to understand the current state of knowledge amidst an overwhelming growth in literature of TT, catching a glimpse of emerging trends, terminology used, journals, authors and countries that mostly address regarding this subject, key actors that support science development in this matter, reference studies in the field along with further fruitful directions of research. Despite the inductive nature of the research not yet reaching its maturity, TT is on the right path as scholars started looking outwards, with rapidly increasing volume of new publications that are solid-based research, new methods, components and adapted-frameworks coming into the academic scene. All the results found in this study mirror the same pattern that leads to an evolution of TT in the next years as more authors, journals, publishers, and countries engage, more collaborations are formed, new methods and perspectives are being considered, different connections are discovered between TT and other disciplines, and more attention is drawn towards supporting this area of science development. Findings suggest that transformative tourism will most likely steal the scene of the tourism industry as it presents a continuous growth in interest. Yet, future studies are constantly needed to track advancements in this field, as research is a continuous process that adapts and changes over time, needing constant updates and clarifications to keep the pace with the growing rhythm of TT.
Despite the aforementioned contribution, the study has some limitations. First, even though consisting of multiple sources collected from four databases to have a better coverage on the subject, there may still be a fraction of yet undiscovered knowledge waiting to be further explored through the search of other databases as well. In spite of incorporating a timeframe of twenty-four years of knowledge in TT, the results from 2022 are considered yet to be completed as research ended on 1 May 2022. Therefore, as the trendline rhythm is constantly changing, the number of publications, citations, or collaborations will certainly experience variation towards the end of the year. As most of the literature surrounding the notion of TT is still new in the field, dimensions, such as number of citations and h-index, might considerably change over time and therefore needs to be further examined. The research algorithm also draws some limits. Although for the accuracy of the study the focus was only on journal articles, there are still a considerable number of conference proceedings, doctoral theses and books that were excluded yet that could bring more dimension to the actual state of knowledge. The conducted investigation was based on English-only articles (except few bilingual papers) as they overwhelmingly dominated the TT publications, yet underestimating research using other languages could bring a more diverse and in-depth analysis on the subject. Even if a combination of keywords consisted of general terms to generate a broader spectrum of articles and not limit the research, there might still be other combinations that could lead to other publications related to TT, and therefore other keywords and combinations must be further explored.
Author Contributions: All authors, K.A.R., S , .D., O.R.C. and F.P. contributed equally to the research presented in this paper and to the preparation of the final manuscript. All authors have read and agreed to the published version of the manuscript.