Page Rank

Page Rank or PageRank (PR) is a link analysis algorithm that assigns a numerical weighting to each web page in the Web, with the purpose of "measuring" its relative importance within the World Wide Web. In the real world it was without doubt that the invention of PageRank method had changed the entire search engine industry dramatically as it significantly improved the quality of the search results.

PageRank was developed at Stanford University by Larry Page (hence the name Page-Rank) and later Sergey Brin as part of a research project about a new kind of search engine. The project started in 1995 and led to a functional prototype, named Google, in 1998. Shortly after, Page and Brin founded Google Inc., the company behind the Google search engine. While just one of many factors which determine the ranking of Google search results, PageRank continues to provide the basis for all of Google's web search tools.

In the essence, PageRank algorithm was built on the logical assumption that the more links from different web pages pointing to a web page (let's say page A), the more important (and also the more valuable) the page A is. As the Web is linked from one page to another, links coming from 'important' web pages are more valuable than links coming from 'less important' pages.

Google has made the following description:

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".

Google assigns a numeric weighting from 0-10, 0 for 'unimportant' and 10 for 'most important' ones, for each webpage on the Internet; this PageRank denotes the site�s importance in the eyes of Google. The scale for PageRank is logarithmic and roughly based upon quantity of inbound links as well as importance of the page providing the link. Being a logarithmic scale, it means that to increase PageRank from 5 to 6 will require much more new incoming links from external web sites than the number of new incoming links required to increase PageRank from 4 to 5.

PageRank should not be confused with search result rank. PageRank is an indicator how popular is a web page on the Web Wide World, while search result rank depends on the relevancy of a web page to particular search terms we use in searching information via search engine. Web page with low PageRank with proper search engine optimization still could rank high in the search results.