thumb|Visual abstraction of several documents being connected by [[hyperlinks]]
thumb|alt=Vannevar Bush.|Engineer [[Vannevar Bush wrote "As We May Think" in July 1945 in which he described the Memex, a theoretical proto-hypertext device which in turn helped inspire the subsequent invention of hypertext.]]
thumb|[[Douglas Engelbart in 2009, at the 40th anniversary celebrations of "The Mother of All Demos" in San Francisco, a 90-minute 1968 presentation of the NLS computer system which was a combination of hardware and software that demonstrated many hypertext ideas]]
Hypertext is text displayed on a computer display or other electronic devices with references (hyperlinks) to other text that the reader can immediately access. Hypertext documents are interconnected by hyperlinks, which are typically activated by a mouse click, keypress set, or screen touch. Apart from text, the term "hypertext" is also used to describe tables, images, and other presentational materials with integrated hyperlinks. Hypertext is one of the key underlying concepts of the World Wide Web, where Web pages are often written in the Hypertext Markup Language (HTML). As implemented on the Web, hypertext enables the easy-to-use publication of information over the Internet.
Etymology
The English prefix "hyper-" comes from the Greek prefix "ὑπερ-" and means "over" or "beyond"; it has a common origin with the prefix "super-" which comes from Latin. It signifies the overcoming of the previous 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 1965 – wrote:
Types and uses of hypertext
Hypertext documents can either be static (prepared and stored in advance) or dynamic (continually changing in response to user input, such as dynamic web pages). Static hypertext can be used to cross-reference collections of data in documents, software applications, or books on CDs. A well-constructed system can also incorporate other user-interface conventions, such as menus and command lines. Links used in a hypertext document usually replace the current piece of hypertext with the destination document. A lesser known feature is StretchText, which expands or contracts the content in place, thereby giving more control to the reader in determining the level of detail of the displayed document. Some implementations support transclusion, where text or other content is included by reference and automatically rendered in place.
Hypertext can be used to support very complex and dynamic systems of linking and cross-referencing. The most famous implementation of hypertext is the World Wide Web, written in the final months of 1990 and released on the Internet in 1991.
History
In 1941, Jorge Luis Borges published "The Garden of Forking Paths", a short story that is often considered an inspiration for the concept of hypertext.
In 1945, Vannevar Bush wrote an article in The Atlantic Monthly called "As We May Think", about a futuristic proto-hypertext device he called a Memex. A Memex would hypothetically store — and record — content on reels of microfilm, using electric photocells to read coded symbols recorded next to individual microfilm frames while the reels spun at high speed, and stopping on command. The coded symbols would enable the Memex to index, search, and link content to create and follow associative trails. Because the Memex was never implemented and could only link content in a relatively crude fashion — by creating chains of entire microfilm frames — the Memex is regarded only as a proto-hypertext device, but it is fundamental to the history of hypertext because it directly inspired the invention of hypertext by Ted Nelson and Douglas Engelbart.
thumb|[[Ted Nelson gives a presentation on Project Xanadu, a theoretical hypertext model conceived in the 1960s whose first and incomplete implementation was first published in 1998. He later worked with Andries van Dam to develop the Hypertext Editing System (text editing) in 1967 at Brown University. It was implemented using the terminal IBM 2250 with a light pen which was provided as a pointing device. By 1976, its successor FRESS was used in a poetry class in which students could browse a hyperlinked set of poems and discussion by experts, faculty and other students, in what was arguably the world's first online scholarly community which van Dam says "foreshadowed wikis, blogs and communal documents of all kinds". Ted Nelson said in the 1960s that he began implementation of a hypertext system he theorized, which was named Project Xanadu, but his first and incomplete public release was finished much later, in 1998. During this period, Nelson also proposed using Vladimir Nabokov's 1962 novel Pale Fire as part of a demonstration to IBM, intending to show how hypertext could support complex, non-linear forms of literary analysis. The novel, structured as a long poem with an extensive, self-referential commentary and index, embodied the principles of associative linking and user-directed navigation that Nelson believed defined hypertext. Its layered design enabled readers to follow multiple interpretive paths through the text, resembling the branching structures later implemented in digital hypertext systems. However, IBM chose a more technically conventional presentation, and the literary demonstration was never realized.
Douglas Engelbart independently began working on his NLS system in 1962 at Stanford Research Institute, although delays in obtaining funding, personnel, and equipment meant that its key features were not completed until 1968. In December of that year, Engelbart demonstrated a 'hypertext' (meaning editing) interface to the public for the first time, in what has come to be known as "The Mother of All Demos".
In 1971 a system called Scrapbook, produced by David Yates and his team at the UK's National Physical Laboratory, went live. It was an information storage and retrieval system that included what would now be called word processing, e-mail and hypertext.
ZOG, an early hypertext system, was developed at Carnegie Mellon University during the 1970s, used for documents on Nimitz class aircraft carriers, and later evolving as KMS (Knowledge Management System).
The first hypermedia application is generally considered to be the Aspen Movie Map, implemented in 1978. The Movie Map allowed users to arbitrarily choose which way they wished to drive in a virtual cityscape, in two seasons (from actual photographs) as well as 3-D polygons.
In France, the launch of the Minitel system in 1982 provided widespread public access to interactive digital content via telephone lines and videotex terminals. Minitel allowed users to search directories, make purchases, read news, and access databases using a system of on-screen menus and numbered links. Although it was based on videotex rather than the dynamic linking protocols of later hypertext systems, Minitel introduced many users to the practice of navigating non-linear networks of information. Its use of branching menus and user-selected paths anticipated key aspects of hypertext interaction, particularly the idea of browsing through interconnected data by following associative or logical links. As one of the earliest large-scale deployments of an online information service, Minitel helped familiarize the public with interactive computing and laid cultural groundwork for the broader adoption of hypertext and web technologies in the 1990s.
Between 1984 and 1987 Frank Halasz, Randall Trigg, and Thomas Moran developed NoteCards at Xerox PARC. This early hypertext system was designed to support information analysis and idea processing, employing a central metaphor of "notecards" which operated as discrete units of information that could contain text or graphics. These notecards could be interconnected through typed, directional links, enabling users to create semantically distinct relationships. A key component of NoteCards was the "Browser card," which provided a graphical overview of the structure of linked notecards, facilitating navigation within complex information networks.
Operating on Xerox Lisp machines, NoteCards' primary impact was within the research community rather than as a commercial product. Its most significant contribution to the field of hypertext is often attributed to the insights gained from its use, Halasz identified critical challenges such as search and query in large hypertexts, composite structures, versioning, and collaborative work.
In 1980, Tim Berners-Lee created ENQUIRE, an early hypertext database system somewhat like a wiki but without hypertext punctuation, which was not invented until 1987. The early 1980s also saw a number of experimental "hyperediting" functions in word processors and hypermedia programs, many of whose features and terminology were later analogous to the World Wide Web. Guide, the first significant hypertext system for personal computers, was developed by Peter J. Brown at the University of Kent in 1982.
In 1980, Roberto Busa, an Italian Jesuit priest and one of the pioneers in the usage of computers for linguistic and literary analysis, published the Index Thomisticus, as a tool for performing text searches within the massive corpus of Aquinas's works. Sponsored by the founder of IBM, Thomas J. Watson, the project lasted about 30 years (1949–1980), and eventually produced the 56 printed volumes of the Index Thomisticus the first important hypertext work about Saint Thomas Aquinas books and of a few related authors.
In 1983, Ben Shneiderman at the University of Maryland Human - Computer Interaction Lab led a group that developed the HyperTies system that was commercialized by Cognetics Corporation. They studied many designs before adopting the blue color for links. Hyperties was used to create the July 1988 issue of the Communications of the ACM as a hypertext document and then the first commercial electronic book Hypertext Hands-On!.
In 1985, Grolier's Academic American Encyclopedia on CD-ROM was developed by Activenture. The encyclopedia could be navigated through hypertext links, a full text search engine, and a traditional bookshelf interface.
In August 1987, Apple Computer released HyperCard for the Macintosh line at the MacWorld convention. Its impact, combined with interest in Peter J. Brown's GUIDE (marketed by OWL and released earlier that year) and Brown University's Intermedia, led to broad interest in and enthusiasm for hypertext, hypermedia, databases, and new media in general. The first ACM Hypertext (hyperediting and databases) academic conference took place in November 1987, in Chapel Hill NC, where many other applications, including the branched literature writing software Storyspace, were also demonstrated.
Meanwhile, Nelson (who had been working on and advocating his Xanadu system for over two decades) convinced Autodesk to invest in his revolutionary ideas. The project continued at Autodesk for four years, but no product was released.
In 1989, Tim Berners-Lee, then a scientist at CERN, proposed and later prototyped a new hypertext project in response to a request for a simple, immediate, information-sharing facility, to be used among physicists working at CERN and other academic institutions. He called the project "WorldWideWeb".