PageRank is the most important indication of the power of back links but do you know where does the PR come from and how it is distributed? It’s important to know that to avoid mistakes when building links.
Links and PageRank
The Nofollow Attribute
When getting backlinks, mind the nofollow attribute on your links. This attribute marks the links as “not trusted” and tells the search engines to discount them as a vote. That means you get no SEO benefit from them.

