Some key dates in the history of Microsoft Corporation:

1975–Paul Allen and Bill Gates, friends who had co-written a programming language for the Altair hobby-kit personal computer, license it to the makers of the Altair. This programming language is the first Microsoft product.

Jan. 1, 1979–Microsoft moves from Albuquerque, N.M., to the Seattle area.

1980–Microsoft chosen by IBM to create operating system for its first PC. Microsoft buys the software for $50,000 from another company and calls it MS-DOS. Steve Ballmer joins Microsoft.

Aug. 12, 1981–IBM introduces the PC, running on MS-DOS.

1983–Microsoft introduces its Word word-processing program, announces plans to create Windows operating system. Allen resigns as vice president, but remains on the board of directors.

November 1985–Microsoft ships its first version of Windows.

March 13, 1986–Microsoft’s stock goes public.

Aug. 1, 1989–Microsoft introduces earliest version of the Office business software suite.

1991–Federal Trade Commission investigates claims Microsoft monopolizes the market for PC operating systems. Investigation closes two years later without a formal complaint.

January 1, 1994–Bill Gates marries Melinda French on the Hawaiian island of Lanai.

July 1994–U.S. and European antitrust investigations settled; Microsoft agrees to change contracts with PC makers. Settlement is rejected in federal court, then reinstated in 1995.

Aug. 24, 1995–Microsoft launches Windows 95.

Nov. 27, 1995–Microsoft releases Internet Explorer 2.0, challenging Netscape’s Navigator Web browser.

Dec. 7, 1995–Gates details shift in Microsoft strategy to focus on the Internet.

Aug. 6, 1997–Microsoft and Apple Computer agree to share technology and set aside long-standing feud.

Oct. 20, 1997–Justice Department sues Microsoft, says it violated the 1994 consent decree by requiring computer makers to use its Internet browser as a condition of using Windows.

May 18, 1998–Justice Department and 20 states sue Microsoft, alleging it illegally thwarted competition. One state later drops out of the suit.

July 21, 1998–Ballmer becomes president of Microsoft.

Oct. 19, 1998–The antitrust trial begins, continues into summer of 1999.

Nov. 5, 1999–U.S. District Judge Thomas Penfield Jackson releases his findings of fact, which label Microsoft a monopoly.

Jan. 13, 2000–Gates steps aside as CEO, giving the post to Ballmer, remains chairman and becomes chief software architect.

Feb. 17, 2000–Microsoft launches Windows 2000.

June 7, 2000–Jackson orders the breakup of Microsoft into two companies.

Sept. 26, 2000–Supreme Court refuses to hear Microsoft’s appeal of Jackson’s decision, sending the case to a federal appeals court.

Sept. 6, 2001–Justice Department says it will no longer seek a breakup of Microsoft.

November 2001–Microsoft, Justice Department reach tentative deal to settle antitrust case.

Oct. 25, 2001–Worldwide launch of Windows XP.

August 2002–Microsoft unveils business and product changes to comply with Justice Department settlement.

June 23, 2003–Microsoft announces Windows Mobile for handheld computers and phones.

March 24, 2004–European Commission fines Microsoft a record $613 million for antitrust violations, though the sanction is later suspended while Microsoft appeals.

April 2, 2004–Sun settles antitrust claims with Microsoft for $1.95 billion.

June 30, 2004 _U.S. appeals court unanimously approves settlement with Justice Department.

Dec. 22, 2004–An EU court rejects Microsoft’s appeal of the March order.

May 12, 2005–Microsoft shows off new Xbox 360; console hits shelves in November.

July 1, 2005–Microsoft agrees to pay IBM $775 million in cash and $75 million in software to settle antitrust claims.

Oct. 11, 2005–RealNetworks settles antitrust claims with Microsoft for $761 million.

March 23, 2006–Microsoft announces a shake-up in its Windows unit, two days after saying it won’t have its next consumer version of Windows ready for the holiday season as planned.

June 15, 2006–Bill Gates announces plans to withdraw from day-to-day duties at Microsoft in July 2008 so he can focus on his charitable foundation.

Nov. 14, 2006–Microsoft introduces Zune music player.

Jan. 30, 2007–Microsoft releases long-delayed Windows Vista and Office 2007.

Jan. 31, 2008–Microsoft makes unsolicited offer to buy Yahoo for $44.6 billion. Eventually walks away after Yahoo won’t agree to even higher offer, $47.5 billion.

June 27, 2008–Gates steps down from full-time role in company, remains board chairman.