Microsoft released its first Windows operating system, Windows 1.0, in 1985.
Windows 1.0 became available on November 20, 1985. It provided a graphical environment that ran on top of MS-DOS and included programs such as Paint, Write, a calendar, a clock, and a control panel. It was not a completely separate operating system in the modern sense; it extended the capabilities of Microsoft’s DOS platform.
The release followed several years of development and was originally announced under the name Interface Manager. Windows 1.0 used tiled application windows rather than freely overlapping windows, a design choice that changed in later versions. Its early sales were modest, but subsequent releases gradually expanded Windows’ influence on personal computing.
Windows 95 was a much later and more commercially prominent release, arriving in 1995 with the Start button and taskbar. That distinction matters because people sometimes remember Windows 95 as the beginning of Windows itself. Microsoft’s first Windows release was a decade earlier, in 1985.