A reciprocal link is a mutual link between two websites. For example, if website A links to website B, then website B can add a reciprocal link back to website A. The result of a reciprocal link is two websites that link to each each other.
Reciprocal links are typically created for one of two purposes: 1) to establish a partnership between two websites, or 2) to boost search engine ranking. If two websites provide related information, the webmasters may decide it makes sense to link to each other. They can establish an online partnership by providing reciprocal links on their websites. Additionally, if a company or individual owns multiple sites, the webmaster may add reciprocal links to each site so that visitors are aware of the other sites.
Reciprocal linking is also used to boost search engine ranking. Since search engine ranking algorithms factor in the number of incoming links, or "inlinks," a website has, reciprocal links can help increase a website's search engine ranking. However, since search engines also factor in the quality of each site providing an incoming link, not all reciprocal links are beneficial.
NOTE: A reciprocal link may link to any page within a website, not just the page that contains the link back to the site.