TrustRank

TrustRank Algorithm

TrustRank is an algorithm that was published in 2004 as a way of combating spam sites from achieving higher rankings than they deserve. It does this using the assumption that good websites rarely link to bad ones.

For it to work it needs an initial selection of good website which are determined by humans and the level of trust is damped as the distance between links from the good site increases. Given that a patent has been filed it is possible that Yahoo have applied the algorithm to their search engine technology.

However the idea that Google has a similar TrustRank algorithm has been dismissed by Matt Cutts even though a patent application with the same name was filed and later abandoned. A more likely method of link-filtering is through the ageing of links in proportion to their PR.