Archive for December 6th, 2008


Saturday, December 6th, 2008

TrustRank is a concept that has been around several years but it is still only understood by a relatively small number of people.  The purpose of TrustRank is to help Google distinguish between quality web sites and spam sites.  When PageRank was first introduced back in the nineties, it proved to be a great method for identifying popular websites. It was the core concept behind Google’s algorithm and was instrumental in their success.

Nowadays, it is common knowledge that a higher PageRank will generally lead to better listings and this can be achieved by getting links to your website.  Paid links and reciprocal linking schemes are now rife across all sectors of the Internet and a high PageRank is no longer a guarantee of quality or popularity.  Something else was needed to separate the good from the bad, and this is where TrustRank came in.

TrustRank works by manually identifying a small selection of quality websites and assigning them a “trust value”.  TrustRank is then passed on to the pages that these sites link to. This is repeated again and again but the TrustRank diminished each time it is passed.  This is similar to PageRank in the way it is passed from site to site but differs from it in that no web page has an intrinsic TrustRank value, making it more difficult for sites to “artificially” acquire TrustRank through linking schemes.

One of the main concepts behind TrustRank is that good quality sites rarely link to spam sites or other poor quality sites.  The sites that are given an initial value are known as “seed sites” and the best candidates are generally well known professional sites that link to many other sites on merit alone.  Government sites, non profit sites and tightly regulated sites are good candidates because they are particularly unlikely to link to poor quality sites for any reasons.

DMOZ is a good example of a TrustRank seed site; it links to thousands of websites but has a strict linking policy and each website that it links to is manually checked by a human editor.  Of course, it can be argued that where there are human editors there is the potential for manipulation and profiteering. It is certainly true that TrustRank is not perfect but it has done a lot to reduce the visibility of spam sites and increase the quality of the SERPs.