In order to further convince you of the value of backlinks we have to take a look at one crucial factor I have left out so far. Many times the page you are going to be leaving a backlink on is going to have something called a PR or pagerank. Pagerank is the level of relevance that Google has decided to give to this particular page. When you leave a backlink on a page such as this ultimately some of that pagerank will be passed on to your site and it will become more relevant.
Pagerank from Backlinks (Google PR)