PageRank

PageRank® is a Google trademarked ranking algorithm. Created by Larry Page and patented by Stanford University. This algorithm was licensed exclusively to Google in exchange for shares of Google stock. PageRank is a mathematical ranking formula applied to web pages based on the flow of links from other web pages or “back links“. The following flow chart illustrates the concept:

PageRank

Additional information including the complete formula can be found at the Wikipedia article for PageRank