It is widely regarded as one of the greatest threats of our time. Since Brexit and Trump there have been countless news items detailing the populist explosion and how it jeopardises our democracies. But the full story is more complicated than that. To understand the political divisions and crises of today, we must get to grips with the contested concept of populism.Beginning with the earliest recorded cases, Simon Tormey breaks down the defining aspects of populism, what sets it apart from other styles of politics, and asks whether there are meaningful differences between populisms of the left and right. He draws together political theory and contemporary case studies from around the world to form a defining picture of the populist 'moment' in which we are living. The result is a critical yet highly readable introduction to this often misunderstood phenomenon.