Google patent about ranking from backlinks

What is really the value of a backlink? It depends on many factors that have been fully described in the patent 7716225 granted 11 May 2010 and entitled: Ranking documents based on user behavior and/or feature data.

Value of a backlink

It shows how a value is assigned to a link to another page based on the presentation and behavior expected of the user or user class.
The probability of clicking on a link is deduced from several factors, presentation, position, relevance, objectivity.

The presentation of a link

All factors which may influence the probability of the visitor to click on a link are taken into account and reinforces the value of this link.

The independence between the source and target

A link on a site belonging to the same webmaster may be devalued. For this, besides the data known of the engine, it takes into account several factors.

The page with the link and the target

Links are often created in pages that are never modified by the webmaster. If the linked page is it changed, the link considered like a vote, must it retain its value? It gave a vote of something else actually. That's why patent for scoring of document takes into account the evolution in time, and the fact that new links are continually added.

User behavior

It can be directly collected in various ways, on the results pages of the search engine, through the Google toolbar.

The analysis of all these factors are used by Google to construct models that infer user behavior and hence the value to give to a link, and thus the ranking in the results of the linked page.

See also: Backlinks and ranking.