When Larry Page and Sergey Brin built Google, they took as their inspiration the academic process of issuing papers and theses. As mathematicians at Stanford University, they were well placed to do that. Any scientific research paper will have a bibliography of further reading, and in academic circles if your paper is frequently referred to by other writers on the same subject then it is deemed to be an important paper.

They figured that the Internet, as a collection of documents, should be no different so they developed a unique system called pagerank which assigns an importance rating of up to 10 points (Google itself only scores 9) for any individual site.

A more detailed description can be found here but in a nutshell, it is important to have high page rank sites linking into to your site and preferably ones that aren’t linked into lots of other sites.

If a pagerank 7 site has only one link and that is to your site then you will collect the full benefit of that pagerank, but if that site links into hundreds of other sites than you only collect a small proportion of that pagerank.

As far as search engine optimisation is concerned, inbound links are the only ones that count. Reciprocal links are of little,if any, value. It’s the net inbound links to your site and the cumulative pagerank of all those links that matter.

To check your inbound links go into the google search box and type “link:www.yoursite.co.uk”

As a general guide here is an interpretation of your internet importance:

1 – 10          - links  Unimportant
10 – 100      - links  Averagely important
100 – 1000   - links Very important
1000+ links  - Major Importance

Remember that you can always check your pagerank by downloading the Google toolbar [link] but also remember that pagerank is just one component, albeit an important one, in the overall Google Ranking Algorithm and it is a key component
in search engine optimisation strategy.