This chapter discusses the practical and analytical reasons for studying the EU. It presents the EU as a complex and innovative political entity, comprising its member states, its institutions, and its citizens. The chapter presents some of the key theoretical and conceptual approaches to understanding how the EU has developed historically and how it works today. Furthermore, it outlines three broad themes that help the reader make sense of the EU: experimentation and change; power sharing and consensus; and scope and capacity. Finally, it provides an overview of the chapters that follow, which cover topics ranging from an historical overview of the EU’s development to its institutional architecture, from its policy-making process to its democratic credentials, from its key internal policies to its growing role as an actor on the global stage.