1981: DOS.
Microsoft developed the disk operating system to run the then-new IBM Personal Computer. Available in two variations (MS-DOS and PC DOS), it utilized a stark textbased interface and simple one-word user commands.

1985: Windows 1.0.
The inaugural version of Windows was originally going to be called Interface Manager. It was nothing more than a graphical shell (with tiled not overlapping windows) that sat on top of the existing DOS operating system.

1987: Windows 2.0.
The second version of Windows added overlapping windows and came bundled with Microsoft’s Word and Excel applications. It received support from a Windows version of the Aldus PageMaker desktop publishing program.

1990: Windows 3.0.
The third time was the charm. Windows 3.0 was the first commercially successful version of the operating system, selling 10 million copies before the 3.1 upgrade. Market acceptance was driven by its improved multitasking capabilities, as well as a wealth of new Windows-compatible applications.

1992: Windows 3.1.
This was more than a simple point upgrade; version 3.1 not only included the requisite bug fixes, but it was also the first version of Windows to display TrueType scalable fonts.

1995: Windows 95.
This was the big one. The release of Windows 95 was a genuine media event, with customers lined up outside stores waiting for the midnight release of the product. Windows 95 dramatically improved the user interface and moved Windows to a 32-bit platform.

1998: Windows 98.
This was an evolutionary change to the previous version, adding USB support, the FAT32 file system, and the Internet Explorer web browser. (Microsoft released an updated “Second Edition” version of Windows 98 in 1999; it contained mostly bug fixes.)

1992: Windows for Workgroups.
Originally developed as an add-on for Windows 3.0, WFW added the necessary drivers and protocols for peer-to-peer networking.

2000: Windows Me.
This “millennium edition” of Windows upgraded Windows 98’s multimedia and Internet features, added the Windows Movie Maker application, and introduced the System Restore utility. Like Windows 95 and 98, it was positioned as an operating system for consumer not corporate desktops.

1993: Windows NT.
Windows NT wasn’t a simple upgrade from Windows for Workgroups; instead, it was a true 32-bit operating system designed for networked organizations. With improved networking capability and nearbulletproof operation, NT (in its original and subsequent 3.0 and 4.0 versions) became the primary operating system for corporate servers and workstations worldwide

2000: Windows 2000.
This was an evolution from the base Windows NT platform, still targeting the corporate market. It came in five different versions Windows 2000 Professional, Server, Advanced Server, Datacenter Server, and Small Business Server.

2001: Windows XP.
Windows XP was the first version of Windows to bring corporate reliability to the consumer market and consumer friendliness to the corporate market. XP blended the best of the Windows 95/98/Me line with the bulletproof 32-bit operation of Windows NT/2000, and threw in a revamped user interface to boot. Microsoft also extended XP with segment-specific variations, such as Media Center Edition, Tablet PC Edition, and so on.

2007: Windows Vista.
The newest version of Windows expands on XP’s functionality and adds increased security and reliability, improved digital media functionality, and the dazzling Aero 3D user interface. With Vista, Media Center and Table PC versions are built into the operating system.