According to Google, Pagerank is a way of leveraging the “uniquely democratic nature of the web by using its vast link structure as an indicator of an individual page’s value.”
Let’s explain with an example. Take two pages, page X and page Y. Now according to Google, when X links to Y, it is counted as a vote of approval by page X for page Y. However, there’s more. Google doesn’t limit pageranking to just the volume of votes (links) a webpage receives. The search engine also analyses the webpage that voted for the other webpage. So, if a heavyweight webpage casts a vote for your webpage, then it counts more and makes your webpage “important”
Now that you’ve understood what pageranking really is, let’s understand how a website is scored on Google and how Pagerank was introduced.
Developed by Larry Page (hence the name Pagerank), while studying at the Stanford University, Sergey Brin also chipped in while developing the possibility of a new type of search engine. This was the year 1988 and soon after that both, Page and Brin left college to start Google Inc. and till date Pagerank is the backbone of all of Google’s web search methodologies.
Every webpage is assigned a numeric value from 0 to 10 by Google and this number/page is what denotes that page’s importance for Google. Therefore the Pagerank of a specific webpage is approximately based on the quality and quantity of inbound links a page gets as well as numeric value (Pagerank) of these links. Some of the other factors that influence the pageranking of a webpage on Google include relevant keywords on the pages, and real-time visits to the webpage as reported by Google’s toolbar.
Google doesn’t provide any other details about the other factors that influence a webpage pagerank in order to prevent spoofing, manipulation, and “Spamdexing.”