Google has a page ranking system developed by Larry Page and Sergey Brin at Stanford University. Page rank starts from PR-0 and end up on PR-10 where PR-0 is the lowest and PR-10 is the most highest or top Google page rank. The days were gone when search engines return the results of queries on basis of tags, Meta tags, keyword and etc. Although Google emphasize on back links for better page ranking but there are number of hidden factors which can improve the page rank of Web Sites.
The most well-known system for ranking sites based on link data is the simplistic formula developed by Google’s founders – PageRank. PageRank, which relies on log-based calculations, is described by Google in their technology section:
PageRank relies on the uniquely democratic nature of the web by using its vast link structure as an indicator of an individual page’s value. In essence, Google interprets a link from page A to page B as a vote, by page A, for page B. But, Google looks at more than the sheer volume of votes, or links a page receives; it also analyzes the page that casts the vote. Votes cast by pages that are themselves “important” weigh more heavily and help to make other pages “important.”
As Google definition of page rank clearly explains that link of your site on another site will be consider as vote. This definition does not mean that if any site links to your Web sites will consider as vote because Google will look into some factors such as page rank, contents, relevancy before considering the backlink.
The theory goes that if hundreds or thousands of other websites link to you, your site must be popular, and thus, have value. If those links come from extremely popular and important (and thus, trustworthy) websites, their power is multiplied to even greater degrees. Links from sites like NYTimes.com, Yale.edu, Whitehouse.gov and others carry with them inherent trust that search engines then use to boost your ranking position. If, on the other hand, the links that point to you are from low-quality, interlinked sites or automated garbage domains (aka link farms), search engines have systems in place to discount the value of those links.