The European Union is an economic and political union between (after Brexit in 2020) 27 European countries. It was created after World War II as the European Coal and Steel Community in 1951 with six member states, evolving into the European Economic Community in 1958. Its focus is the single market, enabling goods, services, capital, and people to move freely within the EU. It is a supranational, or regional, organization, based on a partial surrender of sovereignty among its member states.
A timeline with a history of the European Union can be found on the EU's Europa website.
The European Union is based on treaties, approved by all member states. Its founding treaty is the Treaty of Rome, with amendments including the Treaty of Maastricht and the Treaty of Lisbon. Human rights within the European Union are protected by the EU Charter of Fundamental Rights.
European Commission brochure: The European Union: What it is and what it does
The EU’s Delegation to the United States: News and links to policy areas and EU websites, including information on travel documents and immigration
European Union Newsroom: EU news and press releases
The ABC of EU Law: EU publication. A summary of EU institutions and the sources of European Union law.
The EU Law Analysis Blog has a 2016 post with a quick introduction and some trouble spots for UK law students in Studying EU Law: A Law Student's Guide
CRS Report RS21372: The European Union: Questions and Answers
Oxford Encyclopedia of EU Law: Articles with analysis of points of EU law, including basis, development, and history. Each article includes citations, a bibliography, select documents, and select cases.
There are four major institutions related to European Union Law: the European Commission, the Council of the European Union, the European Parliament, and the Court of Justice. These institutions and the other EU institutions are identified and linked on Europa’s Institutions page.
EUR-Lex: Institutional Affairs: Links to Summaries of EU Legislation arranged by topics including treaties, EU institutions and bodies, and types of EU law.