Sometimes people are confused why they don’t rank better in SERPs even when their toolbar PageRank increases. The reason for the confusion is that there are two types of PageRank available.
The first one is the Google Toolbar Page Rank. You can download the toolbar from www.toolbar.google.com. The toolbar will show a little green bar at the top of your browser and the number varies from 0-10 (of course, 10 being the highest).
This is important to understand that toolbar PR is not the PageRank that Google use in their algorithm. It is only a rough guide to the true PageRanks, which Google keeps secret. Google toolbar is updated in approximately 6 months(recently it was updated on 27th June 2011). So, you may notice that a website has no toolbar PageRank but ranks well. Try your own search in Google and you will see pages with “lower toolbar PageRank but more relevancy” conquering pages with “higher toolbar PageRank but less relevancy” in SERPs.
Second definition refers to the Google algorithm for sorting the ranking system. This is real PageRank which is used by Google for giving results in SERPs. The number 1 in the SERPs has higher PageRank than the number 2 result etc. for a given keyword term. This PageRank will be altered for different searches. This is a difficult algorithm, but concisely, the more websites are linking to your website the higher PageRank your site will get and is updated as soon as Google finds new information to change their opinion of the value of site’s inbound links.
Some of the important factors required for high quality links are:
1. Relevancy: The first thing to check is the relevancy of the link. Say, if you have a website related to food, then a backlink from sports website would not be considered as much relevant, as compared to another food-related website.
2. PageRank: A link from a high PageRank site has a greater influence in getting high quality backlinks. The higher the PageRank of the site linking to you, the better the link for you.
3. Link Density: If the page you got your link from is having hundreds of links then it becomes hard to determine if the link is valuable or not. Instead, it is better to have a link from lower PR site and your link is one of the few links.