TrustRank is a method of link analysis. Many people use web spam to build up their ranking in search engines. Google's PageRank and other similar methods are automatic and can be subjected to manipulation by pages created only with the intention to mislead the search engines. TrustRank is semi-automatic method which calls for selecting a small set of pages to be checked and evaluated by an expert. Once the trustworthy pages are identified (seed sites), an indexing of each of these web pages is extended outward to similarly reliable and trustworthy pages.