PageRank

In information retrieval, PageRank is algorithm developed by Larry Page and Sergey Brin while at Sanford University. Brin and Page published their article, "The anatomy of a large-scale hypertextual Web search engine", in 1998. Their patent for PageRank was filed in 1998 and issued in 2001.

An alternative is Kleinberg's Hyperlink-Induced Topic Search (HITS).