Eastern Europe is the eastern part of Europe. The term has widely disparate geopolitical, geographical, cultural and socioeconomic readings, which makes it highly context-dependent and even volatile, and there are "almost as many definitions of Eastern Europe as there are scholars of the region". A related United Nations paper adds that "every assessment of spatial identities is essentially a social and cultural construct".

One definition describes Eastern Europe as a cultural (and econo-cultural) entity: the region lying in Europe with main characteristics consisting in Byzantine, Orthodox and minor and limited Ottoman influences.

Another definition, considered outdated by several authors, was created during the Cold War and used more or less synonymously with the term Eastern Bloc. A similar definition names the formerly communist European states outside the Soviet Union as Eastern Europe.

Eastern Europe, home of the bulk of world Jewry until the 1940s, is the birthplace of Hasidic Judaism, Litvak Judaism and several Orthodox churches.