Yahoo! founded in 1994 by Stanford Ph.D. students which began as a hobby and is now recognized as a global brand for information retrieval and shopping online. Offering one of the most comprehensive networks of key services for Web users from around the world and the first online navigational guide on the Web, Yahoo! is the leader in traffic, advertising, household and business user reach. Yahoo! reaches over 237 million unique users in 25 countries and 13 languages.
Their main technology is based on taking Inktomi, Fast, and AltaVista, mixing them up a bit, and applying a new algorithm. The main Yahoo index is compiled of sites that they have crawled themselves and sites that have been added via the Yahoo paid inclusion programme.
Yahoo provide their results to Inktomi, AllTheWeb and AltaVista whilst getting their paid for listings from Overture.