What is Page Rank
PageRank is a link analysis algorithm, named after Larry Page and used by the Google web search engine, that 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 algorithm may be applied to any collection of entities with reciprocal quotations and references.The numerical weight that it assigns to any given element E is referred to as the PageRank of E and denoted by
The value of incoming links is colloquially referred to as “Google juice”, “link juice” or “Pagerank juice”.
A PageRank results from a mathematical algorithm based on the webgraph, created by all World Wide Web pages as nodes and hyperlinks as edges, taking into consideration authority hubs such as cnn.com or usa.gov. The rank value indicates an importance of a particular page. A hyperlink to a page counts as a vote of support. The PageRank of a page is defined recursively and depends on the number and PageRank metric of all pages that link to it (“incoming links”). A page that is linked to by many pages with high PageRank receives a high rank itself. If there are no links to a web page, then there is no support for that page.
Numerous academic papers concerning PageRank have been published since Page and Brin’s original paper.
In practice, the PageRank concept may be vulnerable to manipulation. Research has been conducted into identifying falsely influenced PageRank rankings. The goal is to find an effective means of ignoring links from documents with falsely influenced PageRank.
Other link-based ranking algorithms for Web pages include the HITS algorithm invented by Jon Kleinberg (used by Teoma and nowAsk.com), the IBM CLEVER project, and the TrustRank algorithm.
Source : websiteperformance.org