Link exchange programs connect web masters together who are interested in trading links to each others' web sites. The reason for exchanging links is to drive more traffic to the sites. Link exchange helps web masters by bringing in traffic from the referring page and also by increasing the web page's search engine ranking. Many search engine algorithms add value to web sites that have a large number of links to the page.

Links are typically facilitated by third party programs or online sites that bring web masters together with others who are looking to exchange links. While many of these sites were once free, most of the major link exchange programs have gone to either pay per use or subscription required sites. Many of the better programs periodically verify that the links that are exchanged between webmasters are maintained. If one partner in a program decides to remove the link at some point, the link exchange program will notify the second webmaster who may then decide to contact the individual to request that the link be added, or simply remove the link from the offending site.

Link exchange has declined in popularity in recent years as most of the major search engines have altered their rating algorithm to lower the value placed on two way links. A two way link is a link from a site that also features a link back to the original site. Since most two way links are the result of link exchange programs and not through the web community's level of interest in the web site, the search engine companies realized that two way back links no longer were a valuable estimator of a web site's value.

Most search engines now place a much higher emphasis on one way back links than they do for exchanged links. The reason for this is the assumption that one way links represent genuine community interest rather than just being the result of a transaction. For this reason, many web pages offer one way back links for a fee. Many of these web sites are themselves highly ranked since many of the search engines place a higher emphasis on one way back links from sites that are themselves highly ranked.

It has been said that exchaning links is dead, but reports of its death may indeed be premature. There are still a number of web masters that use link exchange programs to drive up their search engine rankings and, while the major search engines have lowered the value of two way links, most of them do still give them some weight. This means that, while link exchange is not a useful as it once was for SEO purposes, it can still help to effectively market a web site.