Wikipedia is the greatest thing since coffee. Whenever I want to learn something about which I know nothing about, e.g., the history of Antarctica, Ekrima Sa’id Sabri, or Euler’s Theorem, I turn to Wikipedia for an introduction, with references and links to more information. The coverage of topics is immense, and growing all the time. Since I think and write about a lot of not-so-ordinary subjects, I often provide a Wikipedia link as a convenience to you, the reader, who can get a short introduction or definition of a topic that is unfamiliar.
Wikipedia is unlike other encyclopedias, in that it is written by the general public, and not necessarily by a specialist in the field. It has over 2 million registered “users” or writer/editors, with nearly a thousand administrators to oversee the whole process. Presently (June 20, 2010), Wikipedia has 3,328,010 articles.
It is not surprising at all that Wikipedia has had its problems and its critics, particularly by the publishers of the printed encyclopedias. And the best place on the net to get an impartial summary and links to the kerfuffle is — yes, that’s right — Wikipedia!
Is Wikipedia an authoritative source of information? No. For authoritative information, one must go to an acknowledged “authority!” So, in the case of Euler’s Theorem, I’ll go to a mathematics textbook, or a history of mathematics, or even a book on Euler’s Theorem, e.g., Séroul, R. “The Theorems of Fermat and Euler.” §2.8 in Programming for Mathematicians (Berlin: Springer-Verlag, 2000), p.15. But as a source of first resort, Wikipedia is superior to all other information sources available, on– or offline.