Although officially published in November 1985, the Windows 1.0
was first presented to media and public on 10th of November 1983 in New York. As the publishing took longer than intended, the press called Windows as Vaporware
Anyway, Happy Unofficial Birthday, Windows!
As you certainly know, in the beginning Windows was not an operating system but a graphical user interface for MS-DOS and was mostly intended to compete with Apple Lisa
's GUI. In 1988 Apple sued Microsoft for copying their GUI but court rejected these claims.
First published Windows version, the 1.01:
Steve Ballmer in an infamous Windows 1 TV commercial 1985:
(Source: Bill Gates Unveiled Windows 30 Years Ago Today