Link building helps the site in many ways. Through the links you can index the frequent visits to your website. With links, the popularity of your website can increase manifold. With quality links, you will be assured of a good ranking in leading search engines like MSN, Yahoo and Google. If you have a high ranking, and good links, the links will help you to retain your ranking in the engine. In all the cases, you should remember that it is the quality of the links and not the number of back links which will help to increase the popularity of the site. So a SEO professional always stresses on the quality of the links.