Matt Cutts, the Google PR guy says they use OVER 200 different metrics to determine page rank, there are the biggies of course but no one knows all of them. Wish I did. I'd be a billionaire.
As a Google reported there are more than 200 different factors to determine Google Pagerank but sorry nobody explain it well other than Google.
The main Factors are as below. - The best on page Optimization. - Your website must have high quality back links. - Your off page activities must having with unique and meaningful description and as per standard of off page activities.