Yahoo! Inc. is a public corporation and global Internet services company. It provides a range of products and services including web portal, search engine, the Yahoo! Directory, Yahoo! Mail, news, and posting. It was founded by Stanford University graduate students Jerry Yang and David Filo in January of 1994 and incorporated on March 2, 1995. The company is headquartered in Sunnyvale, California.

According to Web traffic analysis companies (including Alexa Internet and Netcraft), Yahoo! has been the most visited Web site on the Internet, with more than 412 million unique users. The global network of Yahoo! websites received 3.4 billion page views per day on average as of October 2005, making it one of the most visited U.S. Web sites.

Yahoo! Search is the second largest search engine on the internet, Yahoo also provides vertical search services such as Yahoo! Image, Yahoo! Video, Yahoo! Local, Yahoo! News, and Yahoo! Shopping Search.

In late 2002, Yahoo began to bolster its search services by acquiring other search engines. In December 2002  acquiring Inktomi. In July 2003 they acquired Overture Services, Inc. and its subsidiaries AltaVista and AlltheWeb. On February 18, 2004, Yahoo dropped Google-powered results and returned to using its own technology to provide search results.

About 88% of total revenues for the fiscal year 2006 came from marketing services. The largest segment of it comes from search advertising, where advertisers bid for search terms to display their ads on the search results, on average Yahoo makes 2.5 cents to 3 cents from each search. With the new search advertising system "Panama" Yahoo aims to increase revenue generated from search. Other forms of advertising which bring in revenue for Yahoo include display and contextual advertising.