The history of Microsoft Windows:

Year   Name        Ver     Features

1985   Windows     1.0     * 16-bit Operating System
1987   Windows     2.x     * Dynamic Data Exchange (DDE)
                           * Preemptive Multitasking
                           * Virtual Machines
1990   Windows     3.0     * Enhanced Mode
1992   Windows     3.1     * More stable
                           * Multimedia
1992   Windows     3.11    * Microsoft Mail
       for                 * Networking Integration
       Workgroups
1993   Windows NT  3.5     * Mainframe Operating System ;)
1995   Windows 95          * New Interface
                           * 16- and 32-bit
1996   Windows NT  4.0     * Windows 95 Interface
                           * 32-bit
1998   Windows 98          * Active interface
                           * More integration
2000   Windows 2000        * Active directory structure
                           * Multiple configurations
2000   Windows ME          * Theoretical last version to
                             contain legacy code.

If you find a copy of Windows 1.0, you should load it on an old computer just to experience it. It is amazing how far computers have progressed in the last 20 years.