Link popularity refers to a ranking assigned to your website by the search engines, and it helps determine the ranking your page gets when someone searches for a particular keyword. Google's "PageRank" number which ranks a sites popularity between 0 and 10 is one of the most common forms of tracking how popular your website is. The PageRank number is on a logarithmic scale very similar to how the Richter scale works when tracking earthquakes. A 7.0 earthquake is 10 times stronger than a 6.0 earthquake but a 8.0 is 100 times stronger than a 6.0 and 1000 times stronger than a 5.0.