...give out significant details about how their system works. Google is no exception to the rule, and they have registered numerous patents to protect their IP, including their PageRank technology.

The good thing for users is that we can access these patents and use their information to our advantage. In a WebmasterWorld thread, users are discussing a Google patent called Information retrieval based on historical data, which some claim reveals details on different types of linking techniques that would attract a Google penalty.

Extracts from the patent which have caused a stir are below:

...A typical, "legitimate" document attracts back links slowly. A large spike in the quantity of back links may signal a topical phenomenon (e.g., the CDC web site may develop many links quickly after an outbreak, such as SARS), or signal attempts to spam a search engine (to obtain a higher ranking and, thus, better placement in search results) by exchanging links, purchasing links, or gaining links from documents without editorial discretion on making links.

...if the content of a document changes such that it differs significantly from the anchor text associated with its back links, then the domain associated with the document may have changed significantly (completely) from a previous incarnation. This may occur when a domain expires and a different party purchases the domain... All links and/or anchor text prior to that date may then be ignored or discounted.

From my understanding I think this extract has the following core messages:

• It's best to build backlinks slowly to avoid penalties.
• Sites that generate a huge number of backlinks very quickly can be considered as spam in some cases.
• All previous backlinks are ignored on sites where the topic of the site has changed.

For some webmasters, this information might be nothing new, but patents are still a good way to confirm popular theories or rumors!

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