Microsoft Corporation is the software company founded by BillGates'. They made MS-DOS, MicrosoftWindows, MicrosoftOffice, MicrosoftAccess, InternetExplorer, VisualBasic, VisualC++, VisualStudio and the MicroSoftDeveloperNetwork development tools. They have also sold a UNIX called Xenix, but all references to this have been wiped from their WebSite (MicrosoftWindows actually has a POSIX compliance layer and they do work with MainSoft? on compatibility with UNIX).
Their main cash cows are MicrosoftWindows and MicrosoftOffice, and to a lesser extent MicrosoftExchange and the SQLServer. All other branches of their product family are of questionable profitability, but thanks to the four aforementioned obscenely profitable products they can afford to indefinitely dominate markets where they never turn a profit. Historically they have harvested their profits from software licenses sold in bulk to OEMs and large corporations under secretively protected terms. In more than a few cases these terms have been designed for heavy handed stifling of competition and have been, if not outright illegal, then at least highly questionable. Antitrust investigations have had some corrective effect on the most egregious offences, but this generally happens long after the fact.
Their street address is 1 Microsoft Way. Some say that's their company slogan too.