Google PageRank

Google's PageRank is a link analysis algorithm that scores each webpage in the Google search engine index database. The PageRank value assigned to each webpage is complicated, and generally only known to Google. However, the Google Toolbar, which integrates into popular web browsers, shows a guide PageRank value. These Google Toolbar values range from 0 to 10.

PageRank 'links at votes'

Google describes PageRank:

“ 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 PageRank value of a webpage is determined by how many other webpages link to this webpage (inbound links). The higher the quantity and the higher the PageRank of the pages that link to the webpage, the higher the PageRank value of the webpage receiving the links.

The PageRank value is only a reflection of the PageRank of the pages linking to it. The PageRank value does indicate the value or quality of the webpage.

The PageRank concept is subject to manipulation, but any benefit is only short-term, as Google identify and penalize abuse of the system.

Google Toolbar

The Google Toolbar has a feature where (once enabled) the approximate PageRank value of the current webpage can be seen, using whole values from 0 to 10. A new webpage will have a value of 0. As a webpage gains more inbound links the PageRank value will increase. Getting a website's home page to a PageRank value of 5 is considered a reasonable easy goal for most SEOs. Increasing the value past 5 requires rather more work. There are few websites with scores of 9 or 10, those being the biggest websites on the internet, i.e. those with the greatest number of inbound links. These sites include Amazon.com, eBay.com, BBC.co.uk and of course Google.com themselves.

The PageRank values are typically referred to as PR0 to PR10.

Being only a guide, the Google Toolbar values are updated about every three months. Therefore the values can be quickly out of date, especially for new websites.

The effect of PageRank in search engine results

PageRank is one of many factors used when search engine search results are ordered and displayed. The relationship of a webpages theme to the search term, and the quality of the content a webpage are more important factors. SEOs often spend much of their time trying to increase the PageRank of a website or webpage, only to neglect the quality of quantity of the content.

Older pages tend to appear higher in search engine results. This is due to the way in which the PageRank algorithm works. Older pages tend to have more inbound links than newer pages, and will therefore appear higher in the results. But remember, PageRank is only one of the factors used in search engine results.

Penalizing abuse or manipulation of PageRank

Google penalizes websites involved with the abuse or manipulation of PageRank. Typical scenarios are link farms , which allow member websites to link to each other, to artificially increase their PageRank. Google identifies and penalizes those involved in such schemes. Do not use them, as you may also suffer a penalty.

Spoofed PageRank

It is easy to manipulate the Google Toolbar PageRank value for a given website. Currently any low PageRank page that is redirected (via a 302 server header meta tag) to a high PageRank page causes the lower PageRank page to acquire the PageRank of the destination page. For example, a new PR0 webpage, with zero incoming links, can be redirected to the Google home page (which has a PR10). In the next PageRank update the PR of the new page will be shown as PR10. This is knows as spoofing, and an identified bug in the system. Webpages PR values can be spoofed to a lower PR value, as well as higher. Do not make use of the bug, you may be penalized for it.

Google's "rel=nofollow" tag

To combat abuse of the PageRank concept Google have proposed a new tag for hyperlinks. The rel=nofollow tag allows webmasters to link to a webpage, but for no PageRank to be passed onto the linked webpage. It is possible to artificially inflate the PageRank of a website by creating many message-board posts, or similar content, with links to the website. Message-board administrators can now make use of the rel=nofollow tag to prevent PageRank being passed onto the website.

History of PageRank

PageRank was developed by Larry Page and Sergey Brin at Stanford University, whilst working on a search engine research project, which would later become Google. The name derives from Larry Page's surname. PageRank continues to feature heavily in Google's web search tools. Whilst the name PageRank is a trademark of Google, the patent is assigned to Stanford University.