If Google engineer Matt Cutts had his druthers, buying links would become an extinct SEO practice.

Cutts has addressed the topic of link-buying on a number of occasions on his blog (Mattcutts.com/blog) and in blog comments elsewhere. He’s admonished webmasters who buy links for PageRank and encouraged webmasters instead to buy only links that have been “nofollowed” — in other words, where the rel=nofollow attribute has been added to the link so that the search engines do not count that link as a vote. He has stated in no uncertain terms that Google considers “buying text links for PageRank purposes to be outside our quality guidelines.”