Number of Backlinks
All major search engines use backlinks to determine the quality of web pages. Google names this rank PageRank, Yahoo calls it WebRank. But they all use the backlinks to determine the importance of the page.
Both Google and Yahoo provide ways to know the amount of inbound links, but Google for some reason shows you different information than what they use to determine your page rank.
SheerSEO software Uses Yahoo's data to provide you with a reliable information regarding the amount of backlinks to your domain. Both current data and historical data are available.
