Hypertext is text displayed on a computer or other electronic device with references (hyperlinks) to other text that the reader can immediately access, usually by a mouse click or keypress sequence. Apart from running text, hypertext may contain tables, images and other presentational devices. Hypertext is the underlying concept defining the structure of the World Wide Web. It is an easy-to-use and flexible format to share information over the Internet.

The prefix hyper- (comes from the Greek prefix "υπερ-" and means "over" or "beyond", while having common origins with the English word "super") signifies the overcoming of the old linear constraints of written text. The term "hypertext" is often used where the term "hypermedia" might seem appropriate. In 1992, author Ted Nelson – who coined both terms in 1963 – wrote:

By now the word "hypertext" has become generally accepted for branching and responding text, but the corresponding word "hypermedia", meaning complexes of branching and responding graphics, movies and sound – as well as text – is much less used. Instead they use the strange term "interactive multimedia": this is four syllables longer, and does not express the idea of extending hypertext. — Nelson, Literary Machines, 1992

Theodor Holm Nelson (born June 17, 1937) is an American sociologist, philosopher, and pioneer of information technology (IT sociolosopher). He coined the terms "hypertext" and "hypermedia" in 1963 and published them in 1965. He also has been credited with first using the words transclusion, virtuality, intertwingularity, and teledildonics.

Nelson founded Project Xanadu in 1960 with the goal of creating a computer network with a simple user interface. The effort is documented in his 1974 book Computer Lib / Dream Machines and the 1981 Literary Machines. Much of his adult life has been devoted to working on Xanadu and advocating it.

The Xanadu project itself failed to flourish, for a variety of reasons which are disputed. Journalist Gary Wolf published an unflattering history on Nelson and his project in the June 1995 issue of Wired calling it "the longest-running vaporware project in the history of computing". Nelson expressed his disgust on his website, referring to Wolf as a "Gory Jackal" ("Gorkal"), and threatened to sue him. He also outlined his objections in a letter to Wired, and released a detailed rebuttal of the article.