A Link Exchange describes the relationship between two or more websites that is designed to build reciprocal backlinks between websites. The objective of a link exchange is to improve the page rank of the participating websites and webpages.
This practice has been used for some years, and as such Google has updated its algorithms to spot when link exchanges are being used too much. Webmasters can search for Googles guidelines on Link Exchange practices to determine whether link building in this way will be beneficial to a website’s ranking, or whether it will negatively affect page rank.