The European Union (EU) is a political and economic partnership that represents a unique form of cooperation among sovereign countries. The Union is the latest stage in a process of integration begun after World War II, initially by six Western European countries, to foster interdependence and make another war in Europe unthinkable. Today, the EU is composed of 28 member states, including most of the countries of Central and Eastern Europe, and has helped to promote peace, stability, and economic prosperity throughout the European continent. The EU has been built through a series of binding treaties, and over the years, EU member states have sought to harmonize laws and adopt common policies on an increasing number of economic, social, and political issues. EU member states share a customs union, a single market in which goods, people, and capital move freely, a common trade policy, and a common agricultural policy. This book serves as a primer on the EU and provides a brief description of U.S.-EU relations that may be of interest in the 113th Congress. This book also asks questions about the democratic credentials of the European Union.