"Windows 9x is the family of Microsoft Windows operating systems that comprises the 32-bit, DOS-based Windows versions: Windows 95, Windows 98, and often also Windows Me,[1] which were produced in the 1990s and 2000. All these Windows releases have internal version numbers in the 4.x series.

Windows 9x consists of both 32-bit and 16-bit code. The Win32 API is entirely 32-bit, but DOS-based components, such as the MS-DOS kernel and many of its device drivers and external commands are 16-bit. Additionally, some of the programs that ship with the operating system, such as ScanDisk and Disk Defragmenter, come in two versions: 16-bit (e.g. scandisk.exe) and 32-bit (e.g. scandskw.exe)."