Windows 3.0 is the third major release of Microsoft Windows, launched in 1990. Its new graphical user interface (GUI) represents applications as clickable icons, instead of the list of file names in its predecessors. Later updates expand capabilities, such as multimedia support for sound recording and playback, and support for CD-ROMs.

Windows 3.0 is the first version of Windows to perform well both critically and commercially. Its GUI was considered a challenger to those of Apple Macintosh and Unix. Other praised features are the improved multitasking, customizability, and especially the utilitarian memory management that troubled the users of Windows 3.0's predecessors. Microsoft was criticized by third-party developers for bundling its separate software with the operating environment, which they viewed as an anticompetitive practice. Windows 3.0 had 10 million sales and was succeeded by Windows 3.1 in 1992.

On December 31, 2001, Microsoft declared Windows 3.0 obsolete and stopped support and updates.