The World Wide Web ("WWW" or simply the "Web") is a global information medium which users can read and write via computers connected to the Internet. The term is often mistakenly used as a synonym for the Internet itself, but the Web is a service that operates over the Internet, just as e-mail also does. The history of the Internet dates back significantly further than that of the World Wide Web.
The hypertext portion of the Web in particular has an intricate intellectual history; notable influences and precursors include Vannevar Bush's Memex, IBM's Generalized Markup Language, and Ted Nelson's Project Xanadu. Paul Otlet's Mundaneum project has also been named as an early 20th century precursor of the Web. The concept of a global information system connecting homes is prefigured in "A Logic Named Joe", a 1946 short story by Murray Leinster, in which computer terminals, called "logics," are present in every home. Although the computer system in the story is centralized, the story anticipates a ubiquitous information environment similar to the Web.
In 1980, Tim Berners-Lee, an English independent contractor at the European Organization for Nuclear Research (CERN) in Switzerland, built ENQUIRE, as a personal database of people and software models, but also as a way to play with hypertext; each new page of information in ENQUIRE had to be linked to an existing page. Berners-Lee's contract in 1980 was from June to December, but in 1984 he returned to CERN in a permanent role, and considered its problems of information management: physicists from around the world needed to share data, yet they lacked common machines and any shared presentation software.