I have read somewhere that Google PR is solely based on the number of backlinks that your website has.
Is that true??

Yes it's true. The only thing that contributes to PR is backlinks.
When i say the only thing, That's a bit simplistic.
While it is just backlinks that can increase PR, It's a combination of 'quality' and quantity ofthose backlinks.

But don't worry about PR, It does nothing.

Still concentrate on getting backlinks, But get backlinks from related sites and sites that will send traffic your way. Getting backlinks for PR is a waste of time.

PR is based on

1. Number of backlinks
2. PageRank of the page from which the backlink is coming
3. Relevancy of the links
4. Number of links on the page from which the backlink is coming.

Originally Posted by etech-martin

3. Relevancy of the links

That one is interesting - where does that come from, and how do you know?

(I see you have the same trouble with these darned numbered bullets!)

Originally Posted by ablaye

I have read somewhere that Google PR is solely based on the number of backlinks that your website has.
Is that true??

Google consider various factors when ranking a page. However, the most important things are the quality, relevancy, and number of back links

Originally Posted by etech-martin

3. Relevancy of the links

Nope. relevancy is nothing to do with PR

I agree with Chris. Relevance might help you in where your pages rank, but it has nothing to do with PR itself.

pr is related with the pr of sites which are giving link to you. for example if a pr 9 web site gives you a link it's better than 5 backlink with pr 4.

Not if there's a million other outgoing links on the PR9 page and only a few on the PR4 pages. Conferred PR is divided between all the outgoing links on the linking page.