Google’s original PageRank patent has just expired. Developed by Larry Page and Sergey Brin at Stanford University in 1996, PageRank is the original algorithm used by Google to calculate the importance of a webpage. In simple terms, the PageRank algorithm is a way of measuring the importance of a webpage by counting the number and quality of its incoming links.
PageRank was one of the first algorithms used for sorting internet search results.
In the United States, utility patents have a term of 20 years from the original filing date. The PageRank patent was filed on January 9, 1998. The expiration of Google’s PageRank patent means that the patent is no longer legally enforceable by Google. And that the original PageRank algorithm is now in the public domain.
For some time between 2000 and 2016, a site’s PageRank was displayed on the now defunct Google Toolbar as a number between 0 and 10. Back then, spammers were abusing PageRank by inflating their backlinks. Many spammers were buying and selling high PageRank links for hundreds or even thousands. Google eventually removed PageRank from public sight in 2016.
Although still used as a ranking factor by Google, Google’s days of ranking sites purely based on incoming links are long gone. Google now ranks websites based on a number of signals.
On October 19, 2015, Google filed an updated PageRank patent. The updated patent is titled “Producing a ranking for pages using distances in a web-link graph” and has a different algorithm behind it.
The expiration of the original PageRank patent is a milestone in internet history because Google was built on PageRank.