Today’s World Wide Web is a jungle. How to speedily and smartly sort through it? More than 150 million times a day, users turn to Google, the four-year-old search engine developed by a pair of Stanford University graduate students. Sergey Brin and Larry Page (p.84), PhD candidates in computer science, often found themselves stymied when hunting for data. “Innovation in search had halted,” recalls the Russian-born Brin, who had been researching data mining. Brin and Page dropped their doctoral work and came up with PageRank. The software measures the importance of a given Web page by how many other pages link to it— and by how important those linked pages are. As soon as Mountain View, CA-based Google went live in 1998,it attracted Web surfers who wanted rational search results. Today nobody lists as many Web pages (over two billion) or sorts them as fast (a typical search takes under a second).Now that Google is a success, Brin, once known as a jokester, says he has turned serious. “Jokes are no longer allowed—that’s what our PR people tell me,” the copresident says.