In 2001, the Google search engine rose to prominence. Its popularity was based in part on link popularity and PageRank. The number of other websites and webpages that link. The PageRank of linking pages and the number of links on these pages contribute to the PageRank of the linked page. This makes it easy for Google to order its results by how many websites link to each found page. Google's minimalist interface is very popular with users, and has since spawned a number of imitators.
Google not only uses PageRank but more than 150 other criteria to determine relevancy. The algorithm "remembers" where it has been and indexes the number of cross-links and relates these into groupings. PageRank is based on analysis that was developed in 1952 by Eugene Garfield at the University of Pennsylvania. Google's founders cite Garfield's work in their original paper. In this way virtual communities of webpages are found. Teoma's search technology uses a communities approach in its ranking algorithm. NEC Research Institute has worked on similar technology. Web link analysis was first developed by Jon Kleinberg and his team while working on the CLEVER project at IBM's Almaden Research Center. Google is currently the most popular search engine.