Wikipedia
Since its creation in 2001, Wikipedia has rapidly grown into the largest reference website on the Internet. The content of Wikipedia is free, written collaboratively by people from all around the world. This website is a, which means that anyone with access to an Internet-connected computer can edit, correct, or improve information throughout the encyclopedia, simply by clicking the edit this page link (with a few minor exceptions, such as protected articles and the main page). [from website]
Link to resource:
Wikipedia