HyperText

HyperText is a form of writing read in a non-linear fashion, rather than in a straight line from beginning to end. The text contains links that the reader clicks to move directly to another section of the same document or to other documents. In this way, the reader determines the path they take.

The term hypertext is associated with Ted Nelson, who used the concept in the twentieth century to describe writing not constrained by the format of paper. The underlying idea rests on connecting information as the mind connects ideas, rather than following only a linear page-by-page system.

Structure

A hypertext system consists of two essential components: nodes, which are units of information, and links, which connect the nodes. Links can be unidirectional or bidirectional. When other media—images, sound, video—are added, the result is commonly called hypermedia.

The Web and HTML

The most widespread use of hypertext is the World Wide Web, introduced by Tim Berners-Lee in the late 1980s while working at CERN. The Web uses HTML (HyperText Markup Language) to define the structure of pages and links, and HTTP (HyperText Transfer Protocol) to transfer documents across the network. URLs address the destination of a link.

Earlier systems

Before the Web, experimental hypertext systems existed, such as Nelson's Xanadu project and computer-based systems that emerged in the 1980s. Many of these were limited to a single machine or a small network, unlike the global open Web.