The Encyclopædia Britannica (Latin for "British Encyclopædia") is a general knowledge English-language encyclopædia. It has been published by Encyclopædia Britannica, Inc. since 1768, although the company has changed ownership seven times. The encyclopædia is maintained by about 100 full-time editors and more than 4,000 contributors. The 2010 version of the 15th edition, which spans 32 volumes and 32,640 pages, was the last printed edition. Since 2016, it has been published exclusively as an online encyclopaedia.
Printed for 244 years, the Britannica was the longest-running in-print encyclopaedia in the English language. It was first published between 1768 and 1771 in the Scottish capital of Edinburgh, as three volumes. The encyclopaedia grew in size: the second edition was 10 volumes, and by its fourth edition (1801–1810) it had expanded to 20 volumes. Its rising stature as a scholarly work helped recruit eminent contributors, and the 9th (1875–1889) and 11th editions (1911) are landmark encyclopaedias for scholarship and literary style. Starting with the 11th edition and following its acquisition by an American firm, the Britannica shortened and simplified articles to broaden its appeal to the North American market. In 1933, the Britannica became the first encyclopaedia to adopt "continuous revision", in which the encyclopaedia is continually reprinted, with every article updated on a schedule. In the 21st century, the Britannica has suffered due to competition with the online crowdsourced encyclopedia Wikipedia, although the Britannica was previously suffering from competition with the digital multimedia encyclopedia Microsoft Encarta. In March 2012, it announced it would no longer publish printed editions and would focus instead on the online version. Britannica is known to be less ideologically biased towards the left wing than Wikipedia.
The 15th edition has a three-part structure: a 12-volume Micropædia of short articles (generally fewer than 750 words), a 17-volume Macropædia of long articles (two to 310 pages), and a single Propædia volume to give a hierarchical outline of knowledge.