Page-rank is a link analysis algorithm that assigns a numerical importance to each element that is part of a set of interconnected (hyperlinked) documents such as the World Wide Web. Most of all, this algorithm based on which the page rank works gives a note to each web page on the internet. The page-rank name is a trademark of Google.
Page rank indicates the qualitative value of a web page based on the vast link structure of the web. In essence, Google interprets a link from one page to another as a vote for the second. But Google is paying attention not only to the number of votes, or the links a page receives, it also analyzes the page on which the vote is sent. Votes coming from important pages matter more and thus help to form other important pages.
A link to a page is interpreted as a support vote. The page-rank of a page is defined according to the page-rank of the pages that vote for it, which have a link to the first. A page that is voted on pages with high page rank receives a large page rank. If there are no links to a page then that page does not have support.
Google defines a numerical importance from 0 to 10 any page on the Internet; this page-rank denotes the importance of a site for Google.
The concept of page rank has proven to be vulnerable to manipulation, huge efforts have been made to find sites that have achieved a high page rank using unorthodox and even illegal means and to find ways to ignore them in Google results ( SERPS).