A hyperlink, also called simply "a link", is a reference in a hypertext document to another document or other resource. It is an integral part of the hypertext transfer protocol (http) for the World Wide Web, but it is used also in offline documents, such as .pdf (portable document file, Adobe Acrobat native format) and in .XML (extended markup language). Hyperlink can be used to capture content and save it, view it as a separate document or display it as a part of the reference document.

The history of the hyperlink

The history of the hyperlink began in 1965. Theodore Nelson in "the Xanadu Project" transposed the idea from a fictional microfilm cross-referencing system into the computer world. In a series of books and articles published from 1964 through 1980 the general concept was changed from linking whole microfilm pages to connecting specific lines of computer text.

The primary concept was intended to be used on single computer, however introduction of the DARPA network transformed the idea into creating links between documents and files stored on several networked computers. The idea of connecting parts of a single document via hyperlink arose independently, but was quickly merged into the hyperlink system. Both concepts together were fundamental in creating World Wide Web.

How does a hyperlink work?

A hyperlink has two ends, called anchors, and a direction. The link starts at the source anchor and points to the destination anchor. However, the name hyperlink is often used for the source anchor, while the destination anchor is called the hyperlink target. Every browser shows text hyperlinks somewhat exposed (they usually mark it with a different color). Clicking on the hyperlink activates it and displays the target document.

Hyperlink - Measuring the Net

But hyperlinks are not only the way we surf the Internet. Life on the Web without search engines is almost impossible today, because of unbelievable amount of networked information. Most search engines use so-called "page ranking" to measure which site may contain useful information. This mechanism is mostly based on hyperlink popularity. Although whole idea of "page rank" is more complicated, its general concept is based on a simple rule: the more hyperlinks pointing to a page, the higher rank that page gets.

Of course, each hyperlink has different a value, based on the popularity of the "source" site (This means simply that if your website is a target for a hyperlink placed on big site like CNet, it has a much higher page rank than a site with several hyperlink connections from smaller less important sites). This process is based on the measuring of a hyperlink's quality. Although not perfect, both mechanisms usually work well enough to determine which website has good content and which hasn't.