1985 Microsoft releases Windows 1.0, a 16-bit DOS shell with a graphical user interface that underwhelms a world used to the sophistication of the Apple Macintosh.

1988 David Cutler joins Microsoft to develop a next-generation, 32-bit, micro-kernel-based operating system.

1990 Microsoft releases Windows 3.0, the first successful version of Windows.

1992 Microsoft releases Windows 3.1, a minor update to Windows 3.0 that sold millions and established Windows as a de-facto standard.

1993 Microsoft releases Windows NT 3.1, the first version of Windows NT. Windows NT 3.1 features the Windows user interface and a new 32-bit API for programmers dubbed Win32.

1994 Microsoft releases Windows NT 3.5, which focuses on size and performance issues.

1995 Microsoft releases Windows NT 3.51, and Windows 95, the 32-bit successor to Windows 3.1. Both OSes feature a mostly-compatible Win32 API for programmers, while Windows 95 offers up the new "Cairo" user interface, now known as Explorer.

1996 Microsoft releases Windows NT 4.0, which features the "Cairo" user interface from Windows 95, some enhancements to Remote Access Services (RAS), which becomes known as Dial-up Networking (DUN), and a change in the display driver model, which moves into the kernel.

1997 Microsoft releases Windows NT 4.0 Enterprise Edition, which features Enterprise features such as large memory support and limited clustering capabilities. Windows NT 5.0 Beta 1 is released.

1998 Microsoft releases Windows 98, the Web-integrated successor to Windows 95, and Windows NT 4.0 Terminal Server, which brings multi-user capabilities to NT. Windows NT 5.0 Beta 2 is released. Microsoft announces that Windows NT 5.0 will be named Windows 2000 when it is released.

1999 Microsoft releases Windows 98 Second Edition (SE) with some minor changes and bug fixes.

2000 Microsoft releases Windows 2000, the successor to Windows NT 4.0. Windows 2000 ships in three Editions initially, Professional, Server, and Advanced Server, with DataCenter Server Edition shipping separately in mid-2000. Microsoft also releases the next Consumer Windows, Windows Millennium Edition ("Windows Me"), which is based on the Windows 9x kernel.

2001 - Microsoft to release the next version of Windows 2000, code-name "Whistler". This OS will also work with non-PC devices such as Web terminals and game consoles.