Larry Page and Sergey Brin, PhD students at Stanford, publish in 1998 "The Anatomy of a Large-Scale Hypertextual Web Search Engine", describing PageRank: an algorithm assigning relevance to web pages based on the number and quality of links pointing to them, inspired by academic citation. PageRank models the web as a directed graph and computes the stationary distribution of a random walk. It resolves the manipulability of text-based relevance, becoming the core of Google (founded September 1998), transforming web information access.