Because manual review of the Internet is impractical and very expensive, TrustRank was introduced in order to help achieve this task much more quickly and cheaply.
It was first introduced by researchers Zoltan Gyongyi and Hector Garcia-Molina of Stanford University and Jan Pedersen of Yahoo!
Search engines take a number and quality of backlinks into consideration when assigning a place to a certain web page in SERPs.
One popular method for improving rankings is to increase the perceived importance of a document through complex linking schemes.
[3] The researchers who proposed the TrustRank methodology have continued to refine their work by evaluating related topics, such as measuring spam mass.