Google's predecessor in terms of a popular world wide web search engine was also formed by a pair of Stanford University students. Jerry Yang and David Filo had first created a website that was a "popular guide to the world wide web". In 1995 they registered the yahoo.com which at first was a hierarchical index of websites. Categories branched off into further subheadings that helped web users find their desired resources.
Yahoo was one of the WWW's first web portals, a central point were people could get news, weather reports and other information. This proved to be a popular concept that continues to be in use. 1997 saw Yahoo introducing their webmail service, Yahoo Mail, after acquiring RocketMail.
As the number of webpages continued to increase rapidly, in 2000 Yahoo signed an agreement with Google in order to power web searches on Yahoo. This partnership continued until February 2004 when Yahoo started to use its own resources to provide web results to its users.