Buying Backlinks? The Ultimate Link Buyers Guide
The reason that this plays such a major role in search engine rankings is that the robots and algorithms that are designed by the major search engines can only do so much to interpret whether or not your content is valuable – they are far less efficient at this than human eyes are, and so they have been designed to count backlinks to a site or page almost as a vote of confidence for the content that you have. The way they figure it is that it must be valuable enough to share from an outside property and therefore will be helpful to meet their own search engine goal, which is to serve their users with the most relevant content possible.