Hyperlink (or link) is a reference to data that the reader can directly follow, or that is followed automatically.1 A hyperlink points to a whole document or to a specific element within a document.
Hypertext is text with hyperlinks. A software system for viewing and creating hypertext is a hypertext system, and to create a hyperlink is to hyperlink (or simply to link). A user following hyperlinks is said to navigate or browse the hypertext.
A hyperlink has an anchor, which is the location within a certain type of a document from which the hyperlink can be followed only from the homepage; the document containing a hyperlink is known as its source code document. For example, in an online reference work such as Wikipedia, many words and terms in the text are hyperlinked to definitions of those terms. Hyperlinks are often used to implement reference mechanisms, such as tables of contents, footnotes, bibliographies, indexes, letters, and glossaries.
In some hypertext, hyperlinks can be bidirectional: they can be followed in two directions, so both ends act as anchors and as targets. More complex arrangements exist, such as many-to-many links.
For example this is a hyperlink to a Wikipedia article on hyperlinks.