At the time it launched, Windows actually wasn't a full operating system. Rather, it was a graphical user interface (GUI) that ran on top of DOS. Microsoft Chairman Bill Gates said at launch that Windows 1.0, which carried a suggested retail price of $99 in 1985, was "unique software" that would provide "unprecedented power to users today and a foundation for hardware and software advancements of the next few years." (You can read the full, 32-page Windows 1.0 press kit at this link.)
While that uniqueness has long been up for debate, it is certainly easy to argue that Gates was right about Windows laying a foundation for the future of the personal computer. Windows has been the dominant operating system for the past two decades. Its future as such, however, is in doubt. Computing seems to be undergoing a fundamental shift away from the PC paradigm and toward mobile and tablet-based interfaces.
The graphic below, from ZDNet UK, illustrates the progression of Windows from November 20, 1985 to today.
The following image is a screenshot of Windows 1.0, which sat on top of Microsoft's command-line operating system, MS-DOS.
