TrustRank is a link-based method to separate reputable pages from web spam. Zoltán Gyöngyi and Hector Garcia-Molina of Stanford and Jan Pedersen of Yahoo! described it in a 2004 paper. It comes from research. Google documents no ranking system under this name.
How it works
Experts review a small set of seed pages and pick the reputable ones. The paper reports good results with a seed set of fewer than 200 sites, tested on an AltaVista index. Trust then flows from the seeds along links and is dampened with every step. A page directly linked from a seed receives more trust than one reached through several intermediate pages. Pages that receive little or none are suspect.
What it means for SEO today
SEO articles often use TrustRank to explain why links from established sites seem to matter more. For Google that is not documented. Google’s guide to its ranking systems names PageRank and link analysis, not TrustRank. Metrics such as Majestic’s Trust Flow are separate tool-vendor measures.
Example
A trade portal is in the seed set and links to a manufacturer, which links to a retailer. The retailer is two steps away and gets less trust than the manufacturer. A spam page with no path from trusted pages gets almost none.
Sources
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