1. Introduction
The concept of generations has become a critical factor as the workplace continues to become more diverse than before (Arsenault, 2004; Inegbedion et al., 2020) , with many generations of employees working together (Hurtienne et al., 2022; Moore & Krause, 2021) in the same organisations. Generations represent diversity in organisations as they reflect both the readily detectable and underlying attributes of diversity. While the age attribute, which is germane to diversity (Inegbedion et al., 2020) , is readily detectable (Jackson et al., 1995; Martins & Sohn, 2022) , the attitudinal, thinking, behavioural and belief aspects of the generations refer to attributes which are underlying in nature (Jackson et al., 1995; Martins & Sohn, 2022) . Therefore, the study of generations is vital to understand not only the different aspects of diversity in organisations, but also because generations are at the root of many organisational phenomena (Joshi et al., 2011) .
Generations as a concept are popular with managers, media, consultants, and academics (Lyons & Schweitzer, 2017; Lyons et al., 2015) . This popularity has led to several publications of books by practitioners, reports by consultants, articles in magazines, posts in blogs, and workshops on the differences between generations (Lyons & Schweitzer, 2017; Lyons et al., 2015) . While the corporate world and popular media have increasingly focused on multiple generations as a workplace phenomenon, the academic literature on generations in the workplace has started only since the mid-2000s (Lyons & Schweitzer, 2017) . As generational research grows spurred by its popularity and importance, there are many challenges like generational research continuing to be descriptive, the use of non-theoretical approaches by researchers, the need for more empirical testing of the theoretical contributions (Lyons & Schweitzer, 2017) , the use of USA-centric generational categories and categories based only on the year of birth (Parry & Urwin, 2021) and the lack of agreement on the conceptualisation and measurement of generational differences (Lyons & LeBlanc, 2019) .
While there are many challenges, this article focuses on one of the challenges relating to the different conceptualisations of generations in literature. The differences in the conceptualisation and operationalization of the concept of generations are a challenge as it makes it difficult to compare and collate research insights (Lyons et al., 2015) . The objective of this article is to build on the previous literature (Alwin & McCammon, 2007; Urick et al., 2017) relating to the different conceptualisation of generations in literature on this topic and highlight the different conceptualisation of generations in literature. This article begins with a highlight of practical challenges in the practitioner and academic contexts and will use the input from literature to create more understanding of the different generations. This understanding may help practitioners and academics to be more purposeful in their generational research and be clear about which conceptualisation of generation is being used in their research.
2. Meaning of Generations
Generations is an important concept used by people to describe the relationship between the individual and the society (Alwin & McCammon, 2007) . Even though the researchers use a common terminology of Generations, and the focus is on the individual in the society, the meanings attributed to the notion of generations can appear to be confused as the word Generation has several meanings (Alwin & McCammon, 2007) . The popular and scientific conceptions relating to generations may not coincide as the non-specialists rely on the same terms without conceptual rigour (Alwin & McCammon, 2007) .
The word Generation can have different meanings to different people, even though everyone behaves as if they know the meaning of generations and these differences in the meaning of generations can have an impact on both researchers and practitioners in many ways (Urick et al., 2017) . First, the researchers who are examining generations could be studying different phenomena and could be making inaccurate interpretations leading to problematic results (Urick et al., 2017) . Second, there could be differences between the practitioners in their understanding of the concept of generations and could be speaking about different aspects of generations while discussing with or training others about the differences in generations (Urick et al., 2017) . Third, the press uses the word of generation as if it is understood by everyone similarly (Urick et al., 2017) . This article highlights nine different conceptualisation of generations showing that the concept of generations has different meanings for the researchers, respondents and users of the research studies.
3. Social Forces Perspective of Generations
The first conceptualisation of generation is based on Mannheim’s theory of Generations (Eyerman & Turner, 1998; Pilcher, 1994; Urick et al., 2017) as a social location in the historical-social process (Alwin & McCammon, 2007; Urick et al., 2017) . Mannheim (1952) defined generations as people born in similar cultural and historical context and having the same foundational experiences leading to common characteristics among them (Lyons & Kuron, 2014) . This is also called the social forces perspective (Jones et al., 2018; Lyons & Kuron, 2014: MacKenzie Jr. & Scherer, 2019) which views generations as groups of people shaped by the influences of historical events and the cultural context (Lyons & Kuron, 2014) . Generations are considered as a social force in an organisation instead of just a demographic variable in this perspective (Lyons & Kuron, 2014) . The definition of generations by Mannheim consists of two components that of “common location in a historic time period and a distinct consciousness that is the result of important events of that time” (Joshi et al., 2011: p. 180) . According to Mannheim (1952) , Generations is “a particular kind of identity of location, embracing related ‘age groups’ embedded in a historical-social process” (Mannheim, 1952: p. 292) .
The members of a generation should be “similarly located” and should have experienced the same aspects of the societal processes and should have experienced the same historical events and societal experiences (Mannheim, 1952: p. 297) . A generation is not like a community, which needs its members to have concrete knowledge of each other and when physical proximity of the members is lost, it ceases to exist as a unit and a generation is not like an association formed for a specific purpose as an association has features focused on holding the group together (Mannheim, 1952) . The mental data which makes up the consciousness of its members is important, and it helps the members to form one group (Mannheim, 1952) . The important factor about the mental data is the formative forces which shape, give character and direction to the data and the formative and interpretative principles which link the spatially separated individuals who may never meet (Mannheim, 1952) . It is difficult to find when a generation begins, as birth and death are continuously happening, and an interval exists only in families when there is a gap before the children reach their marital life (Mannheim, 1952) .
The period of a generation could be from 15 years to 30 years based on the understanding that people are still learning in the first 30 years of their life, and they live up to 60 years (Mannheim, 1952) . Karl Mannheim has been identified as “the father of modern generational theory” (Lyons et al., 2015: p. 349) with many of the modern empirical generational studies based on the theoretical contributions of Mannheim (Spitzer, 1973) and ‘The Problem of Generations’ by Mannheim (1952) is considered as a systematic treatment of the concept of generations from a sociological perspective (Pilcher, 1994) . The discussion on the differences between generations can be traced to the works of Mannheim (1952) and the work of Mannheim created a legacy which is enduring even today on the understanding of generations (Joshi et al., 2011) .
4. Generations Based on Genealogy
The second conceptualisation of generations is that of generations as a genealogical definition related to lineage or position in family lineages (Alwin & McCammon, 2007; Urick et al., 2017) . Genealogy refers to the retrieval and ordering of family data into relationship patterns and the family data consists of data like familial data and contextual data based on which socio-historical narrations are built (Durie, 2017) . Genealogy is vertical by defining people in terms of their ancestors and is focused on family descent, connections between the kins and on succession (Lovell, 2008) . On the other hand, Generation is focused on creating horizontal communities, on emphasizing simultaneity and on groups of people who are born around the same time (Lovell, 2008) . Generations based on the genealogical definition reflects the view based on kinships which gives importance to defining the ancestry based on relationships through blood and marriage (Joshi et al., 2011) .
The perspectives on generations based on genealogy help to gain insights on the transmission of values from generation to generation (Joshi et al., 2011) . In an organisational context, genealogy can also refer to the succession by generations in specific organisational roles (Urick & Hollensbe, 2014) . The literature relating to generations based on the genealogical theme in generations focus on tenure in a particular position in an organisation which help individuals to gain a set of experiences, values and skills that can be transferred to their successors (Joshi et al., 2011) . The focus is also on individuals who occupy the roles in organisations gaining tenure in their positions and the separation of generations is based on the location of an individual which in a sequential order is linked through organisational values and routines (Joshi et al., 2011) . The commonality between genealogy and generations is that both use the biological relationships as way to reflect on the social relationships (Lovell, 2008) .
5. Generations as Rites of Passage
The third conceptualisation is that of generations as shared or common rites of passage (Urick et al., 2017) . The rites of passage was proposed by Van Gennep (1961) to indicate the transition and advancement of a person from one social status to another during the life stages of birth, puberty, marriage and parenthood (Wiseman, 2019) . According to Van Gennep (1961) these rites consist of the three stages of 1) Separation in which a person gets separated from the current social status, 2) Transition in which the person moves from the previous social status to a new social status and 3) Reincorporation in which the person gets integrated into the new social status (Wiseman, 2019) . The Rites of passage consist of rituals and ceremonies which are performed to indicate a shift in status from childhood to adulthood (Ginsberg et al., 2014) and consist of public in which an individual or a group of people transition from one stage to another (Eriksen, 2015) . The most important rites of passage mark the transition of an individual from being a child to an adolescent and to an adult (Eriksen, 2015) . These rites of passage are also signified by trials or suffering which are temporary in nature and can also have visible signs like circumcision or tattoos (Eriksen, 2015) .
The rites of passage function as endurance tests requiring the persons to show that they are willing to take up the responsibilities of becoming an adult and gain important knowledge during the transition which will help them transition into a new person (Eriksen, 2015) . Some of the rites of passage in modern societies are confirmation, first communion, marriage, and retirement (Eriksen, 2015) . The intergenerational rites of passage stress a sense of continuity, sense of belonging and sense of integration on the community members (Van der Walt & Bowman, 2007) . There are three kinds of rituals within the rites of passage relating to the 1) Cycle of life like the rites related to birth and death, 2) Crisis rituals in which the community members feel that they are in danger or life-threatening situations like the soldiers who are about to enter battle and 3) Calendrical rituals relating to the meaning of the passage of time like the New Year celebrations (Van der Walt & Bowman, 2007) . There is an interplay between nature and culture in the rites of passage because while intergenerational rites of passage address biological aspects like birth and death, the way in which the meanings are ascribed to these biological events is an aspect of culture (Van der Walt & Bowman, 2007) .
6. Generations as Socially Constructed Identity
The fourth conceptualisation is that of the generation as a socially constructed identity based on perceived differences leading to in-group and out-group formation, which is sustained over a period of time (Urick et al., 2017: p. 274) . Generational Identity is “a form of social identity”, which involves the knowledge that they belong to a generational group, an emotional investment in identifying themselves as its member and recognition of the perceived value involved in belonging to a particular generational group (Lyons & LeBlanc, 2019) . In an organisational context, generational identity refers to an “individual’s knowledge that he or she belongs to a generational group/role” and includes the “emotional and value significance” of the membership to that individual (Joshi et al., 2010: p. 394) . Three generational identities of cohort-based identity, age-based identity, and incumbency-based identity have been proposed within organisations (Joshi et al., 2010) . The cohort-based identity is formed based on the entry into an organisation successively and the successive entry into an organisation leads to the development of unique skill sets, resources and unique experience for each cohort based on their placement in the chronological order (Joshi et al., 2010) .
Cohorts are groups of individuals who join an organisation together and are open to cohort effects which are the normal patterns of responses of the cohort members to the same aspects (Joshi et al., 2010) . The cohort-based identity has a collective identity based on their shared organisational experiences and outcomes (Joshi et al., 2010) . The cohort-based identity is due to the event of organisational entry which creates experiences and outcomes that are common for individuals as they go through the same experiences (Joshi et al., 2010) . The cohort-based identity approach is a coming together of the sociological views, demography based on tenure in organisations and social identity theory to develop a cohort-based generations formed based of entry into an organisation successively (Joshi et al., 2010) . The age-based generational identity is defined as “membership in an age group that shares collective memories developed during the formative years of life” (Joshi et al., 2010: p. 398) . Based on Mannheim’s (1952) work, the two important elements of generations are “common location in a historic time period and a distinct consciousness that is the result of important events of that time” (Joshi et al., 2010: p. 210) .
The beliefs developed through the experiences which are formative in nature influence the attitudes and behaviours of the individuals and the distinct identity and outlook of a generation has relevance in organisational contexts (Joshi et al., 2010) . The age-based generations represent a “unique and collective set of attitudes and values that emerge as a result of the successive ‘coming of age’ of birth year cohorts” and these attitudes and values are unique to each generation shaping the work related attributes in an organisational context (Joshi et al., 2010: p. 397) . The incumbency in a role or job will specify the third type of generational identity in organisations and this is related to a set of knowledge, skill and experiences gained based on the occupation of a role for a period of time in an organisation (Joshi et al., 2010) . Incumbency-based generational identity is defined as “occupancy in an organisational role that must be understood to be finite, has been occupied by a successor, and will be occupied by a predecessor” (Joshi et al., 2010: p. 399) . Incumbency based approaches are applicable in kinship situations also in which generations is conceptualised in terms of tenure in specific roles as grandparent, parent, or child and with younger generations replacing older generations (Joshi et al., 2010) .
Using an incumbency approach, generation is defined as tenure in “a role that may be an office, status, or set of responsibilities” (Wade-Benzoni, 2002: p. 1012) . This helps to understand the intergenerational relationships between those who represent different incumbency-based generations (Joshi et al., 2010) . According to kinship descent research, generations are conceptualised in terms of incumbency in a specific role like a parent, child or grandparent and the key focus area is that older generations are replaced by younger generations and these generations coexist in family units (Joshi et al., 2010) . Joshi et al. (2010) have conceptualised the incumbency based generation in organisations as the occupation of roles which are interdependent in a successive manner by individuals. Incumbency-based generations are evidenced in how vacancies are filled in organisations when a person departs a role and the role is filled by another person and in succession planning and in these incumbency based dynamics the current incumbent acquires a set of knowledge and skills which are passed on to the next incumbent and these incumbents may also work together or compete with each other (Joshi et al., 2010) . According to Joshi et al. (2010) , these three types of identities may co-exist in the same organisation and primacy of any identity from among these three will depend on the organisational context (Joshi et al., 2010) .
7. Lifespan Development Perspective of Generations
The fifth conceptualisation of generations is based on the lifespan development perspective. The lifespan development perspective has been proposed as an alternate and complementary framework for generations as it helps to understand age and development in terms of generations (Rudolph et al., 2021) . The lifespan development perspective positions human development as a process that is lifelong in nature affected by the different influences (Rudolph et al., 2021) . The lifespan developmental perspective defines intra-individual change and inter-individual differences but does not differentiate people based on their birth years or shared experience (Rudolph & Zacher, 2017) . The lifespan model of generations proposes that the influence of the historical and social context happens at the individual level of analysis and not as a shared phenomenon, that the time-based generational operationalisation should not be used and that the focus should be at inter-individual differences (Rudolph & Zacher, 2017) . The lifespan developmental model of generations proposes that the historical events and experiences can affect the developmental outcomes of individuals and can support future research on generational explanations at an individual level (Rudolph & Zacher, 2017) .
8. Collective Consciousness Perspective of Generations
The sixth conceptualisation of generations is based on the collective consciousness perspective as collective consciousness was one of the dimensions used by the participants of a research study to define generations (Urick et al., 2017) . Collective consciousness is related to Mannheim’s theory that the events encountered by the generations shape their consciousness and to the concept of Durkheim (Joshi et al., 2011) . Collective consciousness is also explained by some scholars through the use of identity theories and identification of generations with peers (Boyle, 2023) . Collective consciousness was proposed by (Durkheim, 1893; Walker, 2018) and refers to the collective common beliefs of people which form the basis for social coherence and applies to all societies regardless of size (Malczewski, 2019) . Collective consciousness forms the basis for defining a social entity and can take many forms like religion and family and their subtypes like Catholics and nuclear families (Malczewski, 2019) .
When people share similar experiences or environment, they tend to develop a collective consciousness leading to identification with that particular group of people or community (Walker, 2018) . Collective Consciousness refers to the whole behaviour of the group and not individual identifies of the members of the group and this leads to the development of a new identity based on the experiences of all the members of the group (Walker, 2018) . The participation of members in a collective consciousness happens based on their membership in a particular religion, as family members, as part of an organisation and as part of a community (Walker, 2018) . Within collective consciousness, Durkheim proposed mechanical and organic solidarity in which mechanical solidarity was characterized by similarity and shared nature and organic solidarity was characterized by differentiation and (Walker, 2018) .
9. Generations Based on Contributions of People
The seventh conceptualisation of generations is based on the perspective of contributions by people and this was one of the dimensions used by the participants of a research study to define generations (Urick et al., 2017) . The participants in the research study identified generations based on the outstanding or significant contributions made by groups of people (Urick et al., 2017) . The impact of the accomplishment helped to define a generation and an example are the veterans who made significant contributions to their country by servicing during the war (Urick et al., 2017) . The older participants of the study were the ones to articulate the concept of generations based on significant contributions as the younger participants had not made any significant contributions yet (Urick et al., 2017) . In line with this generational conceptualisation based on contributions, the research by Martinez Jimenez (2009) on women involvement in business showed two generations of contributions and while the first generation of research contribution was focused on the obstacles faced by women while joining the family business, the second generation of research contributions was focused on the opportunities offered by family business to women (Gupta & Levenburg, 2013) .
10. Generations as Sub-Cultures
The eighth conceptualisation of generations is that of generations as Sub-Cultures. In this conceptualisation generations are considered as national sub-cultures which reflect the values that are considered important during a particular period of a country’s history (Cox et al., 2014; Egri & Ralston, 2004) . According to the Generational sub-culture theory “the significant macro level social, political and economic events that occurred during a birth cohort’s impressionable pre-adult years result in a generational identity comprised of a distinctive set of values, beliefs, expectations, and behaviours that remain relatively stable throughout a generation’s lifetime” (Egri & Ralston, 2004: p. 210) . The generational subcultures help to understand the evolutionary process of cultural change and the generational cohorts reflect the values which are emphasized during a particular period encapsulating the nature of cultural change that has taken place in that country (Egri & Ralston, 2004) . The generational sub-cultures help to understand the evolutionary process of change within a culture, and they capture the kind of change that has happened in a particular location (Egri & Ralston, 2004) .
The generational sub-culture theory is of specific interest to researchers focused on cross cultural research due to the complexity of cultures and subcultures around the world triggered by varying combinations of cultural convergence and divergence and migration patterns (Robertson et al., 2012) . According to the generational subculture theory the values acquired by individuals during their childhood and adolescence is exhibited in the adulthood stages and these values tend to be stable throughout the lifetime of an individual (Ralston et al., 2015; Robertson et al., 2012) . Generational subcultures influence the national cultural orientations because the individuals who belong to different generational cohorts have experienced events differently which have influenced their pre-adult years (Ghosh & Chaudhuri, 2009) . The generational subcultures are formed within organisations due to the differences in the perceptions of the generational cohorts (Moss & Martins, 2014) and the members of a generational subculture depend on shared aspects like values, beliefs and attitudes which operate as frameworks to enable these members to think, act and lead (Balda & Mora, 2011) . The generational subculture approach to examining generations is a significant opportunity for further research (Cox et al., 2014; Lee et al., 2022) .
11. Generations as Birth Cohorts
The ninth conceptualisation is that of generations as birth cohorts based on their birth year or biological age, and this conceptualisation prioritises age compared to other factors for defining a generation (Urick et al., 2017) . This is called the cohort’s perspective and views generations as groups of people who are born in a particular period (Lyons & Kuron, 2014) . This conceptualisation has received significant amount of attention, and the popular generational groups like baby boomers, generation X, and generation Y are based on this approach, and these generational categories are based on the year of birth (Urick et al., 2017) . Majority of generational research has focused on defining the samples based on the generational cohorts (Urick et al., 2017) and proximity to events and other differential aspects based on chronology are used to differentiate the cohorts (Parry & Urwin, 2011) . The cohort perspective emerged from the work of Ryder (1965) and is one of the distinct approaches within generational approach and the other being the social forces perspective which is based on Mannheim’s (1952) theory (Lyons & Kuron, 2014) .
12. Discussion
The implication of the nine different conceptualisations of generations in literature is that a common approach to defining generations does not exist and this is supported by Mannheim (1952) also. Generations are an elusive construct and even though there are challenges with studying generations, this is an important area as generation is at the heart of many organisational challenges (Joshi et al., 2010) . The reality of multiple generations at work cannot be denied by anyone as generational differences are becoming a critical factor in the workplace because four generations co-exist in the organisations and the fifth generation is entering the workforce (Burton et al., 2019) . Furthermore, many organisational challenges are related to generational phenomena and its impact are seen on outcomes like hiring, employee retention, planning successors, communication, transfer of skills and sharing knowledge (Joshi et al., 2011) . Generations are as real as race and ethnicity and have been very useful to understand the differences between people (Campbell et al., 2015) .
The limitation of this article is that it is focused only on the different conceptualisations of generations in literature and more research is required to examine whether there are other conceptualisations in literature in addition to what has been highlighted in this article. The different conceptualisations of generations highlight several important considerations for practitioners and academics relating to generational research. The first is that the researcher should ensure that they are clear about the choice of their conceptualisation before they begin their research as this will help to have a coherent approach in their research. Second, the researcher should clearly state their choice of conceptualisation and the relevant definition so that the respondents are able to provide a relevant response and the receivers of the research study are also able to decide on the relevance of the research study to their needs. Third, the researcher should ensure an alignment of the conceptualisation with the research design and data collection methods for ensuring credible research. Fourth, the researcher should be able to reference the relevant scholars related to a particular generational conceptualisation so that their research adds to that specific body of knowledge.
13. Conclusion
This article has highlighted the nine different conceptualisations of generations in literature and considerations for generational research. There is a need for nuanced approaches to the research and application of generations (Parry & Urwin, 2021) and these different conceptualisations offer different approaches to examine the concept of generations. The various conceptualisations of generations show the growing diversity of the concept of generations and each conceptualisation presents a unique opportunity for researchers to make original contributions. It is not about which conceptualisation is better than the other, but the focus should be the research gap and the interest of the researcher. Each conceptualisation of generations has the potential to contribute to both theory and practice as it enables researchers to examine generations and generational differences from different perspectives.
Statements and Declarations
The author did not receive any funding or financial support for this article.