The Gale Encyclopedia of World History consists of a series of 2-volume encyclopedias that provides a broad overview of one particular topic throughout world history, from ancient times until today, with special emphasis placed on how the topic - whether war or government and politics - effects, and is affected by, political, economic and social change in societies. Each set is organized chronologically, by era or event, into 10-30 chapters. Each chapter features an introductory essay on the era or event followed by entries grouped under consistent subheads, such as introduction, major figures, major events and aftermath, that encourage comparisons across eras, events and even centuries. Each set consists of approximately 400 entries, including subject entries and biographies; 300-350 images, including maps; a chronology; a glossary; sources for further study; and a general index.