This book provides a unique contribution to the expanding literature on selftracking technologies and social media through its analysis of users’ practices of using these technologies to self-represent ‘health’ identities and how such performances under the online communities’ gaze affected their ‘health’ behaviours and practices offline. Much research has now attended to the use of self-tracking technologies in multiple settings such as work and insurance schemes, schools, leisure pursuits and in self-tracking communities (Lupton, 2014, 2016a; Fotopoulou and O’Riordan, 2016; Ajana, 2017; Goodyear et al, 2017; Moore, 2017; Kristensen and Prigge, 2018; Moore et al, 2018; Rettberg, 2018; Ruffino, 2018;Spiller et al, 2018; Till, 2018). However, this research has addressed a gap in the literature, which so far has failed to examine the user perspective in the use of these technologies to perform health on social media and how these curated ‘health’ identities affect users’ ‘health’ behaviours in their everyday ‘offline’ lives. Neoliberal rationalities, which have ‘fundamental preference for the market over the state as a means of resolving problems and achieving human ends’ (Crouch, 2011: 7), have shifted public and digital health practices towards self-care through discourses of self-responsibilisation. Self-tracking technologies have largely evaded critique and have primarily been promoted as revolutionary tools for health betterment; they assist with reflexive management of individual risk (Nettleton and Burrows, 2003; Moore and Robinson, 2016) and assume that the accumulation of ‘health’ information and the ‘datafication of health’ (Ruckenstein and Schull, 2017: 262) are better for individual wellbeing. This is a product of wide corporate systemic structures and neoliberal free market strategies of individualised health practices and self-management, adopted by citizens in their construction of identities, for themselves and their communities, to be responsible ‘healthy’ and morally ‘good’ citizens. Within these neoliberal frames, the body becomes subordinated through adoption of technology and control of the mind (Moore and Robinson, 2016).