The most popular system for rating off-page optimisation is Google's PageRank system. A web page that contains a hypertext link to another page can be thought of as casting a vote for the linked page, but all the pages that cast the votes are not equal.
Understanding how PageRank works can help a webmaster create the correct linking structure in a website. Also if a campaign of exchanging links to increase PageRank is to be implemented, it is vital that the importance of factors such as link text is understood.
Counting backlinks from any given web page has long been done. This gives some approximation of a page's importance or quality. PageRank extends this idea by not counting links from all pages equally, and by normalizing by the number of links on a page.
PageRank declares that a link from a rarely visited and rarely updated web page should not have equal weighting to a link from a popular web page. The purpose of the PageRank algorithm is to attach a score, ranging from zero to ten, to every web page. PageRank is a global ranking of all web pages, regardless of their content, based solely on their location in the Web's graph structure.
A popular page like Yahoo will have tens of thousands of pages linking to it indicating that it is a page of fairly high importance. If a web page has a link off the Yahoo home page, it may be just one link but it is a very important one. This should be ranked higher than many pages having more links but from more obscure pages.
Here Page 1 has a Google PageRank of four, which is passed on and divided equally between the two pages it links to, Page 2 and Page 4. Page 3 has a PageRank of Nine, which again is divided equally between the three (two) pages it links to giving giving both Page 2 and Page 4 a PageRank of five.
Google is well aware that there are commercial enterprises that attempt to manipulate the search results in order to get their own and their clients web pages a highly visible position in the search results. PageRank helps to balance this out, as any web page must convince a lot of non-important or an important page to link to it. Google sees this immunity to manipulation as an important property.
As well as the aim of providing the searcher more accurate results, the PageRank algorithm could be used to separate out a small set of commonly used documents which can answer most users' queries, making for a faster search experience. The full database is only used when the smaller database fails to provide an adequate answer to the users query.
In its quest to return only high quality results on its search engine results page, Google will only display a website in its results page if the website that contains the web page has a PageRank. Consequently it is always vital for any newly created site to have at least one incoming link, (and preferably more) from a web page that has PageRank. Any website may be submitted to Google, and it may be spidered and entered into its index. But any website without an incoming link from a web page containing a PageRank will rarely be displayed in Google's search results.
Previous Page Top of Page