Microsoft is an American multinational corporation that develops, manufactures, licenses, supports and sells computer software, consumer electronics and personal computers and services. Its best known software products are the [Microsoft Windows line of operating systems](/product/windows), [Microsoft Office office suite](/product/microsoft-office), and [Internet Explorer]( web browser. Its flagship hardware products are [Xbox](/product/xbox) game console and the [Microsoft Surface](/product/microsoft-surface) series of tablets.Headquartered in Redmond, Washington, Microsoft is the [world's largest software company]( in terms of revenue. It is also considered [one of the world's most valuable companies]( and [one of the most successful startup companies]( of all time by market capitalization, revenue, growth and cultural impact. Microsoft was founded by [Bill Gates](/person/bill-gates) and [Paul Allen](/person/paul-allen) on April 4, 1975, to develop and sell BASIC interpreters for the Altair 8800 microcomputer. The original name, ""Micro-Soft,"" was from a combination of ""microcomputer"" and ""software.""In 1980, the company formed a partnership with [IBM](/company/ibm), allowing Microsoft to sell its software package with the computers IBM manufactured. It rose to dominate the personal computer operating system market with MS-DOS, followed by Microsoft Windows. Since the 1990s, it has increasingly diversified from the operating system market and ventured into hardware such as the [Zune](/product/zune), a digital media player for music, videos, podcasts, and pictures; [Xbox](/product/xbox), a video game console; and [Surface](/product/microsoft-surface), a series of tablets. It has also made a presence on the web with the [MSN](/product/msn) internet portal and [Bing](/product/bing) search engine.Microsoft has also made a number of corporate acquisitions, including [Forethought](/company/forethought), [HotMail](company/hotmail-2), and [Visio Corporation](/company/visio-corporation). In May 2011, [Microsoft acquired Skype Technologies]( for $8.5 billion in its largest acquisition to date.