The World Wide Web Worm (WWWW) was one of the earliest search engines for the World Wide Web (WWW). It was developed in September 1993 by Oliver McBryan at the University of Colorado as a research project.

In practice, any person who has access to the World Wide Web may read the content of Wikipedia on the website wikipedia.org without paying any money. This, however, does not mean that Wikipedia content is fully non-commercial. Copies of Wikipedia content can be sold.

Founded by Jimmy Wales and Larry Sanger on January 15, 2001, Wikipedia is hosted by the Wikimedia Foundation, an American nonprofit organization that employs a staff of over 700 people. Initially only available in English, editions in other languages have been developed.

Because Wikipedia cannot be considered a reliable source, the use of Wikipedia is not accepted in many schools and universities in writing a formal paper, and some educational institutions have banned it as a primary source while others have limited its use to only a pointer to external sources.