PageRank is an algorithm that was developed by Google to provide the most relevant search results to its users queries.  PageRank, along with similar algorithms developed by Google’s competitors for their search engines, is part of the second generation of technologies designed to rate the importance of web pages: the first, which was solely based on keywords in the page content and meta-data, could easily be influenced by those wishing to obtain a higher ranking for their less-relevant pages.

The different with PageRank is that it tries to determine a web page’s relevance to users by attempting to determine its importance.  It does this by assigning it a value of importance that is dependant upon the number of web sites that link to that page, taking into account the importance value, or PageRank, of those pages.  The PageRank is computed iteratively, and it is found that the PageRank values converge fairly rapidly.

Although it is much better than simple keyword-based ranking algorithms, PageRank is not infallible: we have an internet where advertising revenue can make up most - and quite frequently all – of a web site’s income and the people that run these web sites will always be trying to trick the system into giving their pages a higher PageRank.   One of Google’s attempts to counter this is their Google Toolbar browser plugin.

Google Toolbar is a free tool which provides a number of useful functions in a convenient location: the users web browser window.  Google’s payoff is that it gets to track the behaviour of actual users.  This allows them to see whether their PageRank algorithm is accurate in assigning high PageRank values to the most relevant web pages and, just as importantly, low values to those that are irrelevant and try to fool the system.