Microsoft, one of the world's largest companies by market capitalization, launched Windows in 1985.
Windows 1.0 was released on November 20, 1985. It provided a graphical operating environment that ran on top of MS-DOS and included early programs such as a calculator, calendar, clock, notepad, and Paint.
Microsoft had already become associated with MS-DOS, but Windows developed into the company's defining consumer operating-system family. Later releases, including Windows 3.0, Windows 95, Windows XP, and Windows 10, greatly expanded its reach on personal computers.
Windows is not the same thing as MS-DOS. MS-DOS was a command-line operating system, while early Windows supplied a graphical interface. Microsoft now earns revenue from a broad portfolio that also includes Azure, Microsoft 365, Xbox, and enterprise software.