Political theory at Cambridge has sometimes been associated with ‘realism’, in contrast to moralised or idealised views of politics. There are many different ways to be a realist about politics, including the Realpolitik of international relations. Some realists are interested in power; some in legitimacy; some in chance. But how well equipped is any form of realism to make sense of politics in the twenty-first century, when so much of what it refers to has migrated online? Do we even know what makes politics real any more? This lecture will explore the varieties of realism in political theory, to ask what it might mean to have a realistic theory of politics in the age of the internet.