Defining childhood is problematic due to the spatial and temporal fluidity of prevalent ideas and laws pertaining to children. On one level, the definition used by many human geographers and other social scientists reflects the 1989 UN Convention on the Rights of the Child, which defines childhood as the period up to 18 years of age. However, while this implies that children are defined by their chronological age, a collection of studies encompassed by the term 'the new social studies of childhood' has highlighted the complex and contested nature of the term child. This work has highlighted how childhood is socially constructed, and as such is historically and culturally specific rather than reflecting any biologically essentialist reality. Moreover, there is no universal category of child as children's lives and experiences are diverse, inextricably linked to other aspects of their social identity such as gender, ethnicity, class, (dis)ability and shaped by the places where they live, go to school, work, play, etc. As such it is important to remember the global differences and complexities inherent in children's lives and experiences. Furthermore, rather than conceptualizing children as immature, yet to reach the social maturity of adults, human geographers along with colleagues in other social science disciplines (re)conceptualize children as human beings, worthy of investigation in their own right. In addition to providing new theoretical and conceptual understandings of childhood, many human geographers seek to work with children in order to transform their lives at a variety of levels including the local, global, social, political, and economic.