The Win32 API first introduced with Windows NT was adopted as the standard 32-bit programming interface, with Win16 compatibility being preserved through a technique known as "thunking".A new GUI was not originally planned as part of the release, although elements of the Cairo user interface were borrowed and added as other aspects of the release (notably Plug and Play) slipped.
The main architect of the system was Dave Cutler, one of the chief architects of VMS at Digital Equipment Corporation (later purchased by Compaq, now part of Hewlett-Packard).
its intentions to develop a successor to both Windows NT and Windows 3.1's replacement (Windows 95, code-named Chicago), which would unify the two into one operating system. In hindsight, Cairo was a much more difficult project than Microsoft had anticipated and, as a result, NT and Chicago would not be unified until Windows XP.
It also introduced the first version of System Restore, which allowed users to revert their system state to a previous "known-good" point in the case of system failure.
The first version of Windows Movie Maker was introduced as well.
Windows 9x is a generic term referring to a series of Microsoft Windows computer operating systems produced from 1995 to 2000, which were based on the Windows 95 kernel and its underlying foundation of MS-DOS, Internal release versions for versions of Windows 9x are 4.x.
Previous MS-DOS based versions of Windows used version numbers of 3.2 or lower.
Microsoft went on to release five different versions of Windows 95: OSR2, OSR2.1 and OSR2.5 were not released to the general public; rather, they were available only to OEMs that would preload the OS onto computers. The USB support in Windows 98 was more robust than the basic support provided by the OEM editions of Windows 95.
Some companies sold new hard drives with OSR2 preinstalled (officially justifying this as needed due to the hard drive's capacity). It also controversially integrated the Internet Explorer browser into the Windows GUI and Windows Explorer file manager.
Microsoft Windows scored a significant success with Windows 3.0, released in 1990.
In addition to improved capabilities given to native applications, Windows also allowed users to better multitask older MS-DOS based software compared to Windows/386, thanks to the introduction of virtual memory.
Windows NT, which was aimed at professional users such as networks and businesses, used a similar but separate version number between 3.1 and 4.0.