Cross linking refers to the development of linking stuck between two sites. Whether or not they are owned by the same person, cross linking is the process on which the internet is built. It allows users to reference sites with content similar to that which they are already viewing, and may be of further interest to them.Cross linking also serves an appealing purpose in terms of search engine optimization. Link popularity is one of the main factors involved in how search engines determine the value, weight and relevance of sites on a given topic. This calculation is then reflected in the site's search ranking.