The Amazing PageRank Patent

It is amazing, because it has made Google a billion dollar company. US Patent 6285999 is owned by Stanford College. The inventor is Larry Page, one of the two founders of Google. For that reason, this patent is extremely interesting to those in SEO, a.k.a. Search Engine Optimization, or what may be described as the art of getting your page on Google.

The patent, which you can find here, is a rather important one. Although, it should be expiring by January 2017 (its priority date is 10th January 1997).

In the abstract, it is described as:

“A method assigns importance ranks to nodes in a linked database, such as any database of documents containing citations, the world wide web or any other hypermedia database. The rank assigned to a document is calculated from the ranks of documents citing it. In addition, the rank of a document is calculated from a constant representing the probability that a browser through the database will randomly jump to the document. The method is particularly useful in enhancing the performance of search engine results for hypermedia databases, such as the world wide web, whose documents have a large variation in quality.”

In simple language, it’s a means of assigning value to hypertext documents, based on the ranks of documents citing it. A second factor is the constant probability that a user will get to that document after following links through random documents.

Unfortunately, for the citations to be ranked themselves, the rank of documents citing those citing documents must also be ascertained. This is why Mr. Page wrote that, the method requires:

“obtaining a plurality of documents, at least some of the documents being linked documents, at least some of the documents being linking documents, and at least some of the documents being both linked documents and linking documents, each of the linked documents being pointed to by a link in one or more of the linking documents; assigning a score to each of the linked documents based on scores of the one or more linking documents; and processing the linked documents according to their scores.”

Steps to PageRank.

1. Get a bunch of documents, preferably all of them linked to each other, whether one way or two;
2. Assign scores to some linked documents based on scores of other documents linking to it;
3. Process linked documents according to their scores.