Not every backlink has the same quality. Even with the original PageRank algorithm backlinks from websites with a high PageRank were rated higher than those with low PageRank. But since even the PageRank is still relatively easy to manipulate, some other factors are still sought.

The Trust Rank is a term introduced by Yahoo algorithm based on a manual selection of good websites. These assigned a so-called TrustScore they turn pass on Linked Sites. This is especially the search engine spam are limited.

Backlinks have a different power. This power is made up of several factors that affect the page on which the link is placed. These include PageRank, TrustRank, link popularity, etc.