Page rank

Many times we hear the term Page Rank, but we don't usually understand what it is and how to use it.
Page Rank is an analysis algorithm that aims to assign a weight to each hyperlink document based on multiple factors as numbers of Indexed Pages, how big a website and Domain Age.
The weight ranges from 1 to 10 and is the most common case in the World Wide Web. The weight counts the importance of the document.
The named page rank is a trademark of Google. Its algorithm is patented by Stanford University.