A link is a reference in a web page text that functionally provides the opportunity to jump to another web page or to another place on the same web page. By clicking on the link, the reference is opened in the same window or in a new window or tab (depending on the browser setting). A backlink is when a link from another web page refers to a different web page. The number of backlinks that refer to a web page largely determines the calculation of the Google PageRank algorithm.

Backlinks are also generated by text link exchange, the creation of texts for article directories or catalogs in order to improve the general ranking of a web page. Backlinks are then only perceived by search engines as relevant links for the Google PageRank if they are defined as so-called follow links.