It has been known for some time in the world of SEO that backlinks do have a benefit to your website. Google stats that you are not allowed to try and gain positions by buying backlinks but still many companies do it. Google compares a backlink to a vote for your site and says that they should be acquired naturally not by paying for them. They can penalise a website for buying backlinks by demoting it on the search engine results pages or even removing it completely. This being said, many people still do it and it works. When looking for links, do not be tempted to go to a company that is offering you hundreds of links for small monthly fee. These links will often do more harm than good and should be avoided. Instead invest in a linking system that ensures all your links are on relevant sites.