I own and operate a website called YouReview. It’s a simple website that is a wiki and allows anyone to upload details about a business or product and add comments and reviews. We get emails sometimes with people (usually SEO consultants or website owners) who are extremely concerned that links from YouReview are hurting their Google ranking.
Since it’s creation, YouReview has automatically used “nofollow” on all outgoing links. Since we can’t manually review links for quality and we don’t want to contact the owners of every possible link, the easiest and safest thing to do is globally add nofollow.
In a nutshell, nofollow means that Google will not follow those links, and will not count them as it calculates search engine rankings.