To understand what Wikipedia is, you may find it very helpful to understand what Wikipedia is not. Wikipedia’s goal is not, as some people think, to become the repository of all knowledge. It has always defined itself as an encyclopedia—a reference work with articles on all types of subjects, but not as a final destination, and not as something that encompasses every detail in the world. (The U.S. Library of Congress has roughly 30 million books in its collection, not to mention tens of millions of other items, by comparison to about two million articles in Wikipedia). Still, there’s much confusion about Wikipedia’s scope.
Wikipedia has a well-known policy (to experienced editors, at least) stating what kinds of information belong in the encyclopedia. The sister projects that the Wikimedia Foundation supports, such as Wiktionary, fulfill some of the roles that Wikipedia does not.
The Wikimedia Foundation has seven projects that are parallel to Wikipedia, plus a project called the Commons, where pictures and other freely-usable media are stored for use by all projects in all languages (Figure B-1).
Figure B-1. The Wikimedia Foundation has eight parallel projects, the oldest of which is Wikipedia, plus the Commons, a central repository of pictures and other media.
Several of the projects listed in Figure B-1 overlap (or potentially overlap) ...