AbstractThis chapter sets the context for the whole book by describing the broad context of digital transformations focusing on digital platforms across many domains in contemporary life. Platforms are now a key type of societal infrastructure governing many social, institutional and interpersonal interactions. The chapter then introduces literature describing how platforms are increasingly understood in relationship to families. This is both in terms of the family as a social unit and how the family conducts its interior and exterior lives through or ‘on’ platforms. The chapter describes the theories and concepts that have been used to explain how families use platforms to ‘compose’ themselves and how families are addressed and identified as a social unit through and by digital platforms. Contemporary ideas of the family itself are of course in a change of flux and the chapter goes onto describe how the sociology of the family is reconceptualising what the family might mean in the context of radical social restructuring and individualisation. The chapter ends by trying to conceptualise the relationship between families and platforms and how this relationship may be better understood by researching the activities of platformization.