Search technology, once relegated to library science departments and remote corners of computer science labs, went mainstream with the Internet, spawning such once-giant brands as Lycos, AltaVista and Yahoo. These engines proved that the Web could be indexed, but they failed when it came to giving users what they wanted. April 12, 2004

Stanford students Sergey Brin and Larry Page figured out how to use the structure of the Internet -- the way pages link to one another -- to put the most relevant items at the top of a search list. Ultimately, this set the standard, and gave their firm, Google, a massive lead in the industry. April 13, 2004

If Web users don't pay for a search, how do search engines make money? Karr traces the ways these companies earn cash, from sponsored links to ads that somehow seem to know exactly which page to appear on. April 14, 2004

A $1 billion-a-year industry has sprung up offering advertisers and other businesses advice on how to get the most consumer traffic out of their Web pages. Most are ethical, but some specialize in building pages that trick search engines into thinking they're more important than they are. The engines, naturally, fight back. April 15, 2004

Search engines may soon use personal information to return better search results. Google's plan to offer an e-mail service that delivers ads based on e-mail keywords has privacy watchdogs nervous. April 16, 2004