links building serves several purposes. 1. Bringing visitors to your site: the more links you have on the net, the more exposure you get, and the more likely that people will come to your site. 2. Google and other search engine see external links as an indication of the site relevance and importance. It is important to notice that that not necessarily means that the more the better. Sometimes the quality of the site the link is on is more important than the amount of links your site has.