What company did Bill Gates start?

Bill Gates started Microsoft with Paul Allen in 1975 when a company called Altair (makers of micro-computers) became interested in some software the two college students were writing. Originally Micro-Soft, the name was inspired by this first project, creating SOFTware for MICRO-computers. 
Before Microsoft, Gates and Allen had already created a successful software used to analyze traffic patterns in Seattle. They would have started a company together then, but Gates' parents wanted him to finish school first.
Microsoft is now the leading provider of personal computer operating systems (Windows), as well as programs that do word processing (Word), manage email (Outlook), and create spreadsheets (Excel), presentations (PowerPoint), and databases (Access). The company has also branched out to games and gaming systems (Xbox), Smartwatches (Band), computer accessories, mobile devices, and more.
The company generates billions of dollars in revenue and is a household name in the United States.