Google’s PageRank Technology:
PageRank was developed at Stanford University by Larry Page (hence the name Page-Rank) and Sergey Brin as part of a research project. PageRank (is a probability distribution )is a link analysis algorithm which assigns a numerical weighting to each element of a hyperlinked set of documents, such as the World Wide Web, with the purpose of “measuring” its relative importance within the set.The name PageRank is a trademark of Google. The PageRank process has been patented (U.S. Patent 6,285,999), not assigned to Google but to Stanford University.
Google’s PageRank Defination:
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”.
The Google Toolbar’s PageRank feature displays a visited page’s PageRank as a whole number between 0 and 10. Google has not disclosed the precise method for determining a Toolbar PageRank value. Google engineer Matt Cutts, have publicly indicated that the Toolbar PageRank is republished about once every three months.
The Google Directory PageRank is an 8-unit measurement. These values can be viewed in the Google Directory. Unlike the Google Toolbar which shows the PageRank value by a mouseover of the greenbar, the Google Directory does not show the PageRank values.The Google Directory is the only service offered by Google where PageRank directly determines display order.
Google is known to actively penalize link farms and other schemes designed to artificially inflate PageRank.
Other Popular Algos are:
# Hilltop algorithm
# PigeonRank
# TrustRank
Source Wikipedia
