Microsoft Windows

Microsoft Windows is a family of Operating Systems developed by Microsoft. It currently uses the Windows Explorer shell.

The first versions of Windows were an operating environment for DOS. Later versions (9x) used DOS as a bootstrapper. Any version of Windows that uses the NT Kernel does not rely on MS-DOS.

Windows for DOS
During this time, Windows was a desktop environment for DOS, an OS inspired by CP/M. There is a dispute about whether it can be considered an operating system. One side points to the fact that it did include it's own graphics drivers and program API, which is usually considered a component specific to operating systems, however on the other side the argument is that it extensively used the MS-DOS API, and relied on MS-DOS in order to boot. The last version in this family is Windows for Workgroups 3.11.

Windows 9x
In 1995, Microsoft launched Windows 95, which it marketed as a full 32-bit operating system. In fact, the architecture devised for Windows 95, and used for Windows 98 and Windows ME, was a hybrid 16/32-bit system. MS-DOS API's were still used to perform certain low-level tasks, albeit the 9x range also supported the Win32 API created for use with Windows NT. In Windows 9x, MS-DOS is primarily used as a recovery environment, and a bootstrapper for the OS itself. The Windows 9x family of operating systems was discontinued with Windows XP, which merged the NT and 9x codebases. The last version of Windows in this family was Windows ME, released in 2000.

Windows NT
Windows NT (New Technology) is the current family of Windows operating systems. It is based on the NT kernel, which was originally intended for OS/2 3.0. The NT kernel is a multi-architecture operating system kernel, which currently has releases for the x86, AMD64 and ARM processor families. The first version of Windows NT was NT 3.51. This naming scheme continued until Windows 2000. Microsoft has always intended to merge the 9x and NT code bases; they had three successive projects which started with this intent. Windows 2000 never achieved this goal, mainly due to deadline issues. Windows "Neptune" was cancelled, and was eventually merged with another project. This merged project eventually created Windows XP, which succeeded in merging the two codebases at long last. Since then, the NT codebase has continued to mature. The current NT family operating system is Windows 10, released in July 2015.