The World Book Encyclopedia is an encyclopedia published in the United States. It is self-described as "the number-one selling print encyclopedia

Encyclopedia

An encyclopedia is a type of reference work, a compendium holding a summary of information from either all branches of knowledge or a particular branch of knowledge....

 in the world." The encyclopedia is designed to cover major areas of knowledge uniformly, but it shows particular strength in scientific, technical, and medical subjects. It is based in Chicago

Chicago

Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...

, Illinois

Illinois

Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...

. The first edition (1917) contained eight volumes. New editions have since appeared every year except 1920, 1924, and 1932, with major revisions in 1929 (13 volumes), 1947 (19 volumes), 1960 (20 volumes), and 1988 (new typeface and page design, and some 10,000 new editorial features).

The 1917 edition was published by the Hanson-Roach-Fowler Company, but within two years, World Book became the property of W.F.