Google and FFA pages

If you try to acquire inbound links by using link farms or FFA pages, not only will it hurt your search engine ranking, but you might get permanently removed from the search engine listings. Link farms are sites where you can instantly exchange links with all the sites listed in that directory. FFA pages are pointless link directories. The search engines usually discount any links that come from either of these sources. Now that we understand what link popularity is and how it works, we need to look specifically at how Google measures it. They use a number of variables in their algorithm to calculate your overall link score. The higher your score, the higher you will be ranked in the search listings.
One factor that Google uses in their algorithm, obviously, is the total number of sites linking to you. The more links you have, the higher your score will be. However, their algorithm is a little more complicated than that, and it is possible for a website with fewer links to be ranked higher than a website that has more links.
The reason for this is because Google also measures the quality of your links. If your website is about vitamins, and the site linking to you is a video game site, then that is not considered a quality link. The link still helps your score, but the link would help your score much more if it were from a website whose subject matter is the same as yours.