"Wikipedia is a multilingual, web-based, free-content encyclopedia project based on an openly editable model." - Wikipedia

This online encyclopedia is a collaborative, cooperative effort by volunteer writers to provide up-to-date information on any subject imaginable.

Wikipedia is one of the most popular reference websites online, with millions of visitors every month. There are more than 19 million articles and 82.000 active contributors.

Wikipedia is guided by the following principles, referred to as the Five Pillars:

1. Wikipedia is an encyclopedia.
2. Wikipedia is written from a neutral point of view.
3. Wikipedia is free content that anyone can edit, use, modify, and distribute.
4. Editors should interact with each other in a respectable and civil manner.
5. Wikipedia does not have firm rules.

Wikipedia was launched on January 15, 2001 by founder Jimmy Wales. It began as a website called Nupedia (no longer a website), a peer-reviewed free encyclopedia with highly qualified contributors. Contributors to Nupedia were resistant to the idea of a wiki format, so Wikipedia was formed. Non-English Wikipedias were launched in May of 2001.