The TrustRank is a link analysis method described in a paper by Stanford University and Yahoo! researchers for semi-automatically separating useful WebPages from spam.

Many Web spam pages are created only with the purpose of misleading search engines. These pages, chiefly created for profitable reasons, use various techniques to achieve higher-than-deserved rankings on the search engines' result pages. While human experts can easily identify spam, it is too expensive to manually evaluate a large number of pages.

One popular technique for improving rankings is to increase unnaturally the perceived importance of a document through complex linking schemes. Google's Page Rank and similar methods for determining the relative importance of Web documents have been subjected to manipulation.

TrustRank technique calls for selecting a small set of seed pages to be evaluated by an expert. Once the highly regarded seed pages are manually identified, a crawl extending outward from the seed set seeks out similarly dependable and trustworthy pages. TrustRank's reliability diminishes as documents become further removed from the seed set.

The researchers who proposed the TrustRank methodology have continued to refine their work by evaluating related topics, such as measuring spam mass.