This text sets out the basic rationales and characteristics of European integration, which has been taking place since the end of World War II. It aims to demystify the structure of the EU, the basic forces that make it work and the strengths and weaknesses of what has already been achieved. The author also points out the difficult issues the union now faces at the end of the 20th century: when to to act, how best (and whether) to project power, and how to respect diversity and reconcile competition and solidarity.