The Britannica was first published from 1768–71 in three volumes under the title Encyclopædia Britannica, or, A dictionary of arts and sciences, compiled upon a new plan, partly as a conservative reaction to the provocative French Encyclopédie of Diderot published 1751-66. Although the Britannica was published in a market with established English-language encyclopedias, it quickly grew in popularity and size, reaching 20 volumes by the publication of its third edition in 1801. In subsequent editions, the Britannica was able to recruit eminent authorities in various fields and, up to the 11th edition, published new research and scholarly theories. In particular, the 9th and 11th editions (published in 1875-1889 and in 1911, respectively) are regarded as landmark encyclopedias for scholarship. Beginning with the 11th edition, the American owners of the Britannica chose to simplify and shorten its articles, making them more accessible to lay-readers, with the goal of broadening its North American market. In 1933, the Britannica became the first encyclopedia to adopt a "continuous revision" policy in which the encyclopedia would be revised and reprinted every year, and every article checked at least twice per decade.
Today the Encyclopedia Britannica has 32 volume books, and a Bonus book of resources, and you get a DVD-Rom for 2007 at a cost of $1,395.00 for all.