Follow vs Nofollow Links
Linking between sites helps build search engine rankings and site traffic. The more inbound links a site has, the better it does in Google’s results pages. However, there is a way to stop a link from providing a boost to the target site’s ranking.
These are “nofollow” links. They tell a search engine not to count that link toward search engine rankings. They are used in situations that might be exploited by black hat, unethical SEO programmers.
As a site owner, you don’t want to abuse the nofollow atttribute, because if nobody gets “link juice” from you, they won’t want to let you have it, either. Typically, the nofollow attribute is used only a few select cases where users can submit content without going through the webmaster, like forums and comment pages. Reference links on Wikipedia are also nofollow links.
Follow links, then, are what happens the rest of the time. A link appears on a webpage, such as in a news article or blog post, and search engine crawlers find it and count it toward the value of that post. The more important the originator of the link, the more value it gives to the target site.
However, this does not mean that nofollow links are worthless. They can drive valuable traffic to your site, and even create secondary connections of higher worth. For example, if you link to a blog post on a relevant forum, and a writer for a major news source cites it when writing her article, you get a vary valuable follow backlink out of your nofollow link post.
Follow vs nofollow attributes are really pretty simple, but knowing how to make use of them gets more complicated. To many users, nofollow attributes are invisible, since the addition of the tag is invisible to end users of a forum or blog site. But they are anything but invisible to Google.