The World Factbook, also known as the CIA World Factbook, is a reference resource produced by the Central Intelligence Agency (CIA) with almanac-style information about the countries of the world. The official print version is available from the Government Printing Office. Other companies—such as Skyhorse Publishing—also print a paper edition. The Factbook is available in the form of a website that is partially updated every week. It is also available for download for use off-line. It provides a two- to three-page summary of the demographics, geography, communications, government, economy, and military of each of 267 international entities including U.S.-recognized countries, dependencies, and other areas in the world.

The World Factbook is prepared by the CIA for the use of U.S. government officials, and its style, format, coverage, and content are primarily designed to meet their requirements. However, it is frequently used as a resource for academic research papers and news articles. As a work of the U.S. government, it is in the public domain in the United States.