AS what i got from different web sites here is some extraction

“A reciprocal link is an agreement between two webmasters to provide a hyperlink within their own website to each other’s web site. Generally this is done to provide readers with quick access to related sites, or to show a partnership between two sites. Reciprocal links can also help to increase traffic to your web site in two ways. First you will probably have some viewers visit your site from clicking the reciprocal link directly. Secondly, most Internet search engines also take into account the number of web sites which contain links to your web site; the more hyperlinks to your site found, the higher up in the search engine rankings (depending on the search term) you’ll find your site.”