From The Electronic Labyrinth:
Hypertext is the presentation of information as a linked network of nodes which readers are free to navigate in a non-linear fashion. It allows for multiple authors, a blurring of the author and reader functions, extended works with diffuse boundaries, and multiple reading paths.
The term "hypertext" was coined by Ted Nelson, who defined it in his self-published Literary Machines as "non-sequential writing" (0/2).
Many subsequent writers have taken hypertext to be a distinctly electronic technology--one which must involve a computer. For example, Janet Fiderio, in her overview "A Grand Vision," writes:
Hypertext, at its most basic level, is a DBMS [database management system] that lets you connect screens of information using associative links. At its most sophisticated level, hypertext is a software environment for collaborative work, communication, and knowledge acquisition. Hypertext products mimic the brain's ability to store and retrieve information by referential links for quick and intuitive access. (237)
Our definition does not limit itself to electronic text; hypertext is not inherently tied to technology, content, or medium. It is an organizational form which may just as readily be delivered on paper as electronically.
Jakob Nielsen, the author of Hypertext and Hypermedia, defines hypertext as follows in "The Art of Navigating Through Hypertext:"
Hypertext is non-sequential writing: a directed graph, where each node contains some amount of text or other information....[T]rue hypertext should also make users feel that they can move freely through the information according to their own needs. This feeling is hard to define precisely but certainly implies short response times and low cognitive load when navigating. (298)
For a glimpse at the evolution of hypertext see A Short History of Hypertext.
In the lore that has built up around the links, nodes and interconnectivity of hypertext, Vannevar Bush's 1945 article As We May Think (published in the Atlantic Monthly) is often cited as a visionary glimpse of hypertext. In "As We May Think," Bush proposes the creation of the "memex," a device which enables someone to organize and interconnect information, in effect to enhance memory through associative links:
Our ineptitude in getting at the record is largely caused by the artificiality of systems of indexing. When data of any sort are placed in storage, they are filed alphabetically or numerically, and information is found (when it is) by tracing it down from subclass to subclass. It can be in only one place, unless duplicates are used; one has to have rules as to which path will locate it, and the rules are cumbersome. Having found one item, moreover, one has to emerge from the system and re-enter on a new path.
The human mind does not work that way. It operates by association. With one item in its grasp, it snaps instantly to the next that is suggested by the association of thoughts, in accordance with some intricate web of trails carried by the cells of the brain....
...The first idea, however, to be drawn from the analogy concerns selection. Selection by association, rather than by indexing, may yet be mechanized. One cannot hope thus to equal the speed and flexibility with which the mind follows an associative trail, but it should be possible to beat the mind decisively in regard to the permanence and clarity of the items resurrected from storage.
Consider a future device for individual use, which is a sort of mechanized private file and library. It needs a name, and to coin one at random, "memex" will do. A memex is a device in which an individual stores all his books, records, and communications, and which is mechanized so that it may be consulted with exceeding speed and flexibility. It is an enlarged intimate supplement to his memory.
It is Bush's vision of associative links, rather than the actual mechanics of the memex which have had a lasting influence on the evolution of hypertext technology.
Ted Nelson is credited with the invention of the term "hypertext" to describe an associative system of text-handling. Hypertext is a central element of Nelson's ambitious Xanadu Project:
Xanadu is an overall paradigm - an ideal and general model for all computer use, based on sideways connections among documents and files. This paradigm is especially concerned with electronic publishing, but also extends to all forms of storing, presenting and working with information. It is a unifying system of order for all information, non-hierarchical and side-linking, including electronic publishing, personal work, organisation of files, corporate work and groupware.
On a small scale, the paradigm means a model of word processing where comments, outlines and other notes may be stored conceptually adjacent to a document, linked to it sideways. On a large scale, the paradigm means a model of publishing where anyone may quote from and publish links to any already-published document, and any reader may follow these links to and from the document.
(Excerpted from the Xanadu website)
The linked networks of hypertext documents form, in Nelson's vision, the Docuverse:
Cyberspace is the realm behind the computer screen, the other side of the telephone receiver, just a centimetre beneath the surface of the keyboard, where words and sounds and images and all forms of codified phenomena dance. This is the virtual world in which media mix; the city square of the technological nomad; the new phase space of the economic. Cyberspace is, in theory, unbounded. Everything which can be reduced to zeroes and ones eventually finds its home here--all that can be measured, codified, transacted.
The docuverse is but one slice through this virtual reality, on the axis of media, at the point marked "text." Here lies the dream of the universal library--every word ever recorded knit together in a mosaic of knowledge, just waiting for the holy command to bring it forth. This is the ultimate manifestation of a primal will to closure. The move to cyberspace reifies, as Benedikt has noted, the age-old desire for the Heavenly City, "its radiance like a most rare jewel" (Revelation 21:9). After coming so far, we still find ourselves looking for an Eden, a Xanadu, no less fervently than before.
This radiant vision has been manifest, some would claim, in the hypertextual World Wide Web.
Below are a list of sites which demonstrate how hypertext is being used creatively.