Sharing is a distinct form of interaction championed in digital contexts. Yet the term ‘sharing’ is a site of contestation. There are multiple overlapping imaginaries of sharing, such as sharing as an inherent social norm; sharing as a frictionless form of communication through social technologies; sharing as a fraught practice that, when over-performed, undermines and breaks down relationships and reputations; and sharing as an economic model. Furthermore, the term ‘sharing’ has been appropriated by specific cultural intermediaries at the cost of understanding the material and affective significance of sharing in everyday life. Yet still, there is no sufficient theory or formalisation of sharing, only reappropriations of existing theories – such as gift, reciprocity, knowledge and commodity exchange, and boundary work – that partially explain certain practices of sharing to the exclusion of others. Based on this observation, I argue that we are in need of a framework for theorising sharing as it is experienced in the contexts of digital device use. In response to this need, I set out a theory of sharing as a coherent and consistent set of elements, comprising competencies, materiality and symbolic values.