This chapter introduces the main areas of literature and themes relevant for contextualizing how we might go about and understand researching social media from a discourse perspective. The chapter provides a sense of the kinds of issues that are most salient for us to ask research questions about. It looks at what social media have meant for how we now communicate in society, for the sharing of information and news, and for civic engagement, especially when much of social media use is done rapidly on mobile phones, often while doing other things at the same time. Using examples, it considers the kinds of communication typical of social justice movements. It asks what kinds of communities come together on social media and what binds them. This is considered in the light of how critical discourse analysis would be concerned in regard to democratic principles, and the maintenance and legitimation of social inequalities. The chapter looks at the idea of affective communities, how algorithms shape the kinds of connectivities and points of view we encounter. It looks at the nature of news in the social media landscape and shows that this has huge consequences for our democracies. The chapter ends with a section on ethics in social media research.