Profile: California-based internet and software company best known for its web portal, search engine, news site and mail service with passion for change, going through five chief executives in as many years.
Despite continuing turbulence in corporate managment and numerous rounds of layoffs, more than 500 million visitors continue to use the 12,000-employee company's online properties every month.
Current interim chief executive Ross Levinsohn stepped in after Scott Thompson allegations of having lied on his CV about a computer science degree that did not exist.
Yahoo grew rapidly in the 1990s before skyrocketing during the dotcom bubble and subsequently crashing, but could still boast $4.9bn in revenues in 2011.
Notable products: Yahoo! Mail, Yahoo! Maps, Yahoo! Finance, Yahoo! Sports, Yahoo! Music, Flickr, Yahoo! Movies, Yahoo! Answers, Yahoo! Games, Yahoo! Travel, Yahoo! Shopping, Yahoo! Autos, Yahoo! Real Estate, Yahoo! Groups, My Yahoo! and Yahoo! Messenger.
Key company facts
The company's name is an acronym for "Yet Another Hierarchical Officious Oracle" but founders David Filo and Jerry Yang say they picked the term because they liked the general American definition of a yahoo: "rude, unsophisticated, uncouth".
Yahoo has said it operates a 2-petabyte data warehouse to analyse the live, constantly indexed behaviour of its web visitors' 24 billion events per day. This is more than 10 times larger than the US's Internal Revenue Service database.
After action by European regulators, the company changed its data retention policy and said it would store personally identifiable search information for only 90 days.
1994: Founded by Yang and Filo at Stanford University as "Jerry and David's Guide to the World Wide Web".
1996: Initial public offering on April 12 closes at $33.00, up 270 per cent from the starting price.
1997: Yahoo acquires Four11, whose Rocketmail service is transformed into Yahoo! Mail.
1999: Yahoo acquires Geocities.
2000: All-time high of $118.75 per share reached on January 3.
2001: The stock price hits a post-bubble low of $4.05 on September 26.
2002: Yahoo completes acquisition of employment search engine HotJobs
2004: Replaces use of Google search with own search engine technology, which mainly relies on free web crawl but also has paid inclusion.
2005: Acquires photo service Flickr and launches new blog and social networking service Yahoo! 360°
2006: Retires former front page and announces significant re-organisation of the company.
2007: Revamps mail service with unlimited storage space to compete with Gmail, and introduces oneSearch mobile phone technology.
2008: Microsoft makes unsuccessful $44.6bn bid for Yahoo, as company announces several rounds of major layoffs.
2009: Carol Bartz becomes new CEO.
2010: Announces shut down of Yahoo! Buzz, MyBlogLog and other products.
2011: Bartz fired as CEO after two years of financial lethargy.
2012: Yahoo sues Facebook over 10 patents and is counter-sued in response. The company also announces layoff of 2,000 employees. The short-lived CEO leaves after allegations of an error in his CV.
Closed or defunct services
AltaVista: Web search engine once popular but discontinued in 2010.
Bix: Contest website founded in 2006 but terminated by 2009.
Blo.gs: Directory of weblogs purchased in 2005 then transferred to the company that runs WordPress.
Del.icio.us: Social bookmarking site sold back to AVOS.
Kelkoo: Shopping search engine for Europe acquired in 2004 and spun off in 2008.
Yahoo! 360°: Social networking site and blog host launched in 2005 and closed in 2009.
Yahoo! Auctions: Online auction site shut down in 2007 everywhere except East Asia.
Yahoo! Briefcase: Free file hosting service that closed down in 2008.
Yahoo! Buzz: Community-based news site modeled after Digg but discontinued in 2011.
Yahoo! Geocities: Web hosting service purchased by Yahoo in 1999 but closed in 2009.
Yahoo! HotJobs: Employment search engine acquired by and merged into Monster.com in 2010.
Yahoo! Meme: Social networking service like Twitter and Tumblr but discontinued in 2012.
Yahoo! Player: Computer-based media player that was designed by Yahoo but discontinued.
Yahoo! Podcasts: Beta service shut down in 2007 and folded into Yahoo audio search.
Yahoo! Tech: Service that offered advice for buying electronics closed down in 2010.