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, as e-mail does. The history of the Internet dates back significantly further than that of the World Wide Web.

The origins of the actual World Wide Web can be traced back to 1980, however. It is essentially a merger of IBM's Generalized Markup Language with a very limited implementation of Ted Nelson's Project Xanadu hypertext designs, both of which predate HTML and the World Wide Web by decades. Since its implementation in the 1990s as an academic system for sharing papers, the World Wide Web has evolved far beyond what its creators imagined.

Today, the Web and the Internet allow connectivity from literally everywhere on earth—even ships at sea and in outer space.