You can freely build on How Websites Get Ranked by Importance

What this patent covers

This patent outlines a computer method for assigning an "importance score" to documents within a network, such as web pages (Claim 1). It works by first obtaining a collection of documents where some link to others. Then, it calculates a score for each linked document based on the scores of all the other documents that point to it (Claim 1). For example, if a highly-scored website links to your blog post, your blog post's score would increase. The patent also describes various ways to adjust these scores, such as considering how many links a linking document has (Claim 2) or even how likely a user is to access that linking document (Claim 3). This process helps in organizing and presenting documents based on their calculated importance.

What is now free to use

All 0 claims of US 6285999 are in the public domain. Specifically:

The 0 dependent claims add narrowing limitations and are also free.

What is NOT covered

Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.

• Does not cover ranking documents solely based on the words they contain, without considering incoming links.

• Does not cover ranking documents where the score is not influenced by the scores of other documents linking to it.

• Does not cover ranking systems that only count the number of links to a document, without adjusting for the importance of the linking document itself.

• Does not cover ranking based purely on user behavior metrics like clicks, unless those metrics are used to adjust the linking document's weighting factor (Claim 7).

• Does not cover ranking where a "random traversal" (Claim 10) does not assign rank based on how many times a document has been traversed.

Who is building on this today

Google continues to build on and evolve the principles of PageRank for its search engine, though their current ranking algorithms are far more complex. Other search engines like Bing and DuckDuckGo also use link-based ranking signals, even if their specific algorithms differ. Academic researchers in information retrieval and network science continue to explore and refine graph-based ranking methods.

Products built on expired version of this technology

How to cite this patent in your documentation

Leland Stanford Junior University. US Patent 6285999. Method for node ranking in a linked database. Granted 2001, expired 2018. Now in the public domain.

Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.

PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.