Does page rank depend only on the number of backlinks?

The first thing to keep in mind is that there are two PageRanks. The name appears in your Google toolbar and is updated once every three months or so, and the current name receives regular updates and is used in Google's search algorithm.

The first only provides information for web admins, while the second directly impacts your search rankings.

Now back to your question, does page rank depend only on the number of inbound links, also known as backlinks?

The answer is No.

The number of backlinks certainly plays a role, but Google also carefully evaluates the quality and importance of those links.

By quality, I mean absolute trust in the site you're linking to. A link to Stanford University will have more quality than your sister's blog. Another way to call quality is capacity.

By relevance, I mean the proximity of the content on the website to you and your content. If you have a blog about cats, a link to your sister's blog that only talks about cats will be more important than a link to Stanford University's quantum physics department.

To understand this better, let's consider an example. Suppose you start two blogs, A and B. Both blogs are about technology. In the first blog, you buy 30 backlinks from minor and unrelated sites (most don't even have PageRank, to begin with). In another blog, on the other hand, you publish a good article, and the article links to the front page of TechCrunch.

If you wait three months and keep everything else on the blog, chances are the first page will end up with no PageRank, while the second will end up with a PR1.

Some more interesting facts about PageRank:

• Many people believe that PageRank uses a logarithmic scale, meaning it's harder to increase your PR as you go (i.e., moving from PR5 to PR6 is more complicated than moving from PR2 to PR3).
• The PageRank isn't calculated from 0 to 10; it's just a number used for domain names.
• PageRank is only one of the factors used in Google's search algorithm, so a high PR does not automatically mean a high search ranking.
• Your PageRank can be affected by your internal and external links.
• Content and update frequency does not affect PageRank.