Encyclopædia Britannica it is scarcely used, and reviewers have recommended that it be dropped from the encyclopaedia. The also has color transparencies of human anatomy and several appendices listing the staff members, advisors, and contributors to all three parts of the Britannica. Taken together, the and comprise roughly 40 million words and 24,000 images. The two-volume index has 2,350 pages, listing the 228,274 topics covered in the "Britannica", together with 474,675 subentries under those topics. The "Britannica" generally prefers British spelling over American; for example, it uses "colour" (not "color"), "centre" (not "center"), and "encyclopaedia" (not "encyclopedia"). However, there are exceptions to
Encyclopædia Britannica main competitor was the general encyclopaedia of Ephraim Chambers and, soon thereafter, "Rees's Cyclopædia" and Coleridge's "Encyclopædia Metropolitana". In the 20th century, successful competitors included "Collier's Encyclopedia", the "Encyclopedia Americana", and the "World Book Encyclopedia". Nevertheless, from the 9th edition onwards, the "Britannica" was widely considered to have the greatest authority of any general English language encyclopaedia, especially because of its broad coverage and eminent authors. The print version of the "Britannica" was significantly more expensive than its competitors. Since the early 1990s, the "Britannica" has faced new challenges from digital information sources. The Internet, facilitated by the development of