windows versions :

• Windows 1.0 (1985): The very first version. It introduced a graphical user interface (GUI), mouse support, and cooperative multi-tasking. It featured tiled windows (they couldn't overlap).
• Windows 2.0 (1987): Introduced overlapping windows, which led to a famous lawsuit from Apple. It also saw the debut of Microsoft Word and Excel.

The Windows 3.x Era

This was the series that made Windows a household name and a major success.

• Windows 3.0 (1990) & Windows 3.1 (1992): A massive improvement. It introduced the Program Manager and File Manager, better graphics, and true popularity. Windows 3.1 added TrueType fonts, making it a viable platform for publishing.
• Windows for Workgroups 3.1 & 3.11 (1992-1993): Added built-in peer-to-peer networking and domain support, making it essential for offices.

The Windows 9x Era (Consumer Line)

This line was built on top of MS-DOS but integrated it more deeply. It was known for its "Start" button and desktop but was less stable than the business-focused NT line.

• Windows 95 (1995): A revolutionary release. It introduced the Start button, the taskbar, desktop icons, and long filenames (breaking the 8.3 character limit). It was a massive cultural and commercial phenomenon.
• Windows 98 (1998): Refined Windows 95. It better integrated Internet Explorer with the Windows shell (leading to antitrust issues) and added support for USB, DVD, and FAT32.
• Windows Me (Millennium Edition) (2000): The last of the DOS-based line. It was notoriously buggy and unstable. It introduced System Restore and featured a more consumer-focused look, but is largely considered a failure.

The Windows NT Era (Business/Professional Line)

Developed separately from the consumer line, Windows NT (New Technology) was built for stability, security, and business use from the ground up. It eventually merged with and replaced the consumer line.

• Windows NT 3.1 (1993): The first version of the NT line, released after Windows 3.1, hence the version number. It was aimed at high-end workstations and servers.