And also check the following:
What are the back links?
When a link is placed on someone's website that is pointing to your website, then it is called a back link for your site.
Why It is Important To Get the Back Links
Back links will give you mainly 2 advantages
a) The back links increase the PR of your website
b) The back links drive a share of traffic from the source websites.
c) Your SERPs position is also improved by the back links. Althoug it is not the main factor.
Relation Between Back links and PR
PR of a webpage is directly proportional to the number of quality back links. If you are getting enough back links, then your PR will be boosted in a little time.
But PR will be increased really if your back links are quality back links.
What are Quality Back links
I think a quality back link must have following 3 properties:
a) A back link will be a quality back link if it is from a high PR site, say PR4+
b) If the theme, nature or subject of both websites is same then the back link will be called a quality back link.
c) The anchor text of the back link should be your target key words.
If a back link is having above three properties, then only few of these back links will be giving you a high PR and good traffic.
Be Careful of rel="NoFollow" Tag
You may see a lot of high PR blogs and sites where you can post your comments and can place your site link in signatures. But be aware, that most of these sites are using the "No follow" tag in the links.
Actually a link with a nofollow tag is useless for your website in term of PR. This tag tells the search engines that dont pass the PR to the site where back link is pointing. It will be a simple back link and will not increase your PR.
So before spamming any blog or forum, check if it is a "No Follow" blog/forum or "Do Follow" blog/forum.
And that's end
I think many people will like this post as it is telling the basics of back links and PR. Of course, this is not for advanced users who know all this before