Microsoft Windows released their first operating system in 20 November 1985 which was called Windows version 1.0 and it received little popularity. Windows was originally going to be called "Interface Manager" but their head of marketing at Microsoft, Rowland Hanson, convinced the company that the name Windows would be more appealing to consumers. The first version of Microsoft Windows included a simple graphic programs called Windows Paint, Windows Write, a simple word processor, an appointment calendar, a card filer, a notepad, a clock, a control panel, a computer terminal, Clipboard, and RAM driver. It also included the MS-DOS Executive and a game called Reversi.
Approximately two later Microsoft out with version 2 of Windows was slightly more popular than its predecessor. Most of Windows 2.0 popularity came from the fact that it was a run-time version and its new graphical applications such as Excel and Word for Windows. Windows 2.0 allowed application windows to overlap each other unlike its predecessor Windows 1.0, which could display only tiled windows. Windows 2.0 also introduced more shortcuts keys on the keyboard- and the terminology of "Minimize" and "Maximize", as opposed to "Iconize" and "Zoom" in Windows 1.0. On 17 March 1988, Apple filed suit against Microsoft and HP, accusing them of violating copyrights Apple held on the Macintosh System Software. Apple claimed the "look and feel" of the Macintosh operating system, taken as a whole, was protected by copyright and that Windows 2.0 violated this copyright by looking extremely similar to it.
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 multitask better thanks to the introduction of memory. Windows 3.0's user interface was finally a serious competitor to the user interface of the Macintosh computer. PCs had improved graphics by this time, due to VGA video cards, and the Protected/Enhanced mode allowed Windows applications to use more memory in a more painless manner than their DOS counterparts could. This was the first version to run Windows programs in protected mode.
Windows 3.1 was designed to have backward compatibility with older Windows platforms. As with Windows 3.0, version 3.1 had File Manager and Program Manager, but unlike all previous versions, Windows 3.1 and later support 32-bit disk access which cannot run in real mode, and included Minesweeper instead of Reversi (though Reversi was included in some copies).Windows 3.1 Multimedia PC Version included a media viewer, and the ability to play video files. On 31 December 1993, Microsoft released Windows 3.11 which was not a standalone version of Windows, but rather a software update from Windows 3.1, much like modern Windows service packs. For those who did not own Windows 3.1, full disk sets of Windows 3.11 were available at the time.
Windows NT 3.1, NT 3.5 and NT 3.51
Windows NT 3.1 is the first release of Microsoft's Windows NT line of server and business desktop operating systems, and was released to manufacturing on 27 July 1993. The operating system was designed to run multiple instruction set architectures and multiple hardware platforms within each architecture. The platform dependencies are largely hidden from the rest of the system by a kernel mode module called the HAL (Hardware Abstract Layer). The version number was chosen to match the one of Windows 3.1, the then-latest operating environment from Microsoft, on account of the similar visual appearance of the user interface. Two editions of NT 3.1 were made available, Windows NT 3.1 and Windows NT Advanced Server. It was succeeded by Windows NT 3.5 in September 1994. One of the primary goals during Windows NT 3.5's development was to increase the speed of the operating system. New features in Windows NT 3.5 include a new startup screen, VFAT, support for I/O completion ports  and the Microsoft DHCP and WINS clients and DHCP and WINS server. Windows NT 3.51 was the third release of Microsoft's NT line of operating systems. It was released on 30 May 1995, nine months after Windows NT 3.5. The release provided two notable feature improvements; firstly Microsoft Windows released PowerPC architecture on NT 3.51. The second most significant enhancement offered through the release was that it provides client/server support for interoperating with Windows 95, which was released three months after NT 3.51.
Windows 95 is a consumer-oriented graphical user interface-based system. Which was released on August 24, 1995 by Microsoft. It features significant improvements over its predecessor, Windows 3.1, most visibly in the graphical user interface (GUI). There were also major changes made at lower levels of the operating system. In the marketplace, Windows 95 was a major success, and within a year or two of its release had become the most successful operating system ever produced.
Microsoft released Windows NT 4.0, which features the new Windows 95 interface on top of the Windows NT kernel (a patch was available for developers to make NT 3.51 use the new UI, but it was quite buggy).
On 25 June 1998, Microsoft released Windows 98. It included new hardware drivers and better support for the FAT32 file system which allows support for disk partitions larger than the 2 GB maximum accepted by Windows 95. The USB support in Windows 98 is far superior to the token, unreliable support provided by the OEM editions of Windows 95. It also controversially integrated the Internet Explorer browser into the Windows GUI and Windows Explorer file manager, prompting the opening of the United States v. Microsoft case, dealing with the question of whether Microsoft was abusing its hold on the PC operating system market to unfairly compete with companies such as Netscape. In 1999, Microsoft released Windows 98 Second Edition, an interim release. One of the more notable new features was the addition of Internet Connection Sharing, which was a form of network address translation, allowing several machines on a LAN (Local Area Network) to share a single Internet connection. Second Edition was also much easier to use and much smoother than the first edition of Windows 98.
Microsoft released Windows 2000, in February 2000. It was successfully deployed both on the server and the workstation markets. Amongst Windows 2000's most significant new features was Active Directory, Windows Server domain model, which built on industry-standard technologies like DNS, LDAP, and Kerberos to connect machines to one another. Terminal Services, previously only available as a separate edition of NT 4, was expanded to all server versions. A number of features from Windows 98 were incorporated as well, such as an improved Device Manager, Windows Media Player, and a revised DirectX that made it possible for the first time for many modern games to work on the NT kernel. Windows 2000 is also the last NT-kernel Windows operating system to lack Activation. While Windows 2000 upgrades were available for Windows 95 and Windows 98, it was not intended for home users.[7
In September 2000, Microsoft introduced Windows Me (Millennium Edition), which was the upgraded version Windows 98 with enhanced multimedia and Internet features. 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. System Restore was a notable feature that made its way into Windows XP. The first version of Windows Movie Maker was introduced as well. Many of the new features were available from the Windows Update site as updates for older Windows versions. As a result, Windows Me was not acknowledged as a unique Operating System like Windows 95 or 98. Windows Me was widely criticised for serious stability issues, and for lacking real mode DOS support, to the point of being referred to as the "Mistake Edition" or Me meaning "Many Errors". Windows Me was the last operating system to be based on the Windows 9x (monolithic) kernel and MS-DOS.
In 2001, Microsoft released Windows XP. The merging of the Windows NT/2000 and Windows 95/98/Me lines was finally achieved with Windows XP. The initial release met with considerable criticism, particularly in the area of security, leading to the release of three major Service Packs. Windows XP SP1 was released in September 2002, SP2 came out in August 2004 and SP3 came out in April 2008. Service Pack 2 provided significant improvements and encouraged widespread adoption of XP among both home and business users. Windows XP lasted longer as Microsoft's flagship operation system than any other version of Windows, from 2001 to January 30, 2007, when it was succeeded by Windows Vista.
Windows Server 2003
On April 25, 2003 Microsoft launched Windows Server 2003, a notable update to Windows 2000 Server encompassing many new security features, a new "Manage Your Server" wizard that simplifies configuring a machine for specific roles, and improved performance. A few services not essential for server environments are disabled by default for stability reasons, most noticeable are the "Windows Audio" and "Themes" services; Users have to enable them manually to get sound or the "Luna" look like Windows XP. The hardware acceleration for display is also turned off by default; users have to turn the acceleration level up themselves if they trust the display card driver. December 2005, Microsoft released Windows Server 2003 R2, which is actually Windows Server 2003 with SP1 (Service Pack 1) plus an add-on package.
Windows Home Server
Windows Home Server is a server product based on Windows Server 2003, designed for consumer use. The system was announced on January 7, 2007 by Bill Gates. Windows Home Server can be configured and monitored using a console program that can be installed on a client PC. Such features as Media Sharing, local and remote drive backup and file duplication are all listed as features.
Windows Vista was released on November 30, 2006 to business customers, with the consumer versions following on January 30, 2007. Windows Vista intended to have enhanced security by introducing a new restricted user mode called User Account Control, replacing the "administrator-by-default" of Windows XP. Vista also features new graphics features, the Windows Aero GUI, new applications (such as Windows Calendar, Windows DVD Maker and some new games including Chess, Mahjong, and Purble Place),Internet Explorer 7, Windows Media Player 11, and a large number of underlying architectural changes. Vista has also been the target of much criticism mostly for its high system requirements, its more restrictive licensing terms, the number of authorization prompts for User Account Control and other issues. Apart from all the criticism Vista is also the most used operating system on the internet with approximately 400 million Internet users.
Windows Server 2008
Windows Server 2008, released on February 27, 2008, Windows Server 2008 builds on the technological and security advances first introduced with Windows Vista, and is significantly more modular than its predecessor, Windows Server 2003. At the Professional Developers Conference (PDC) 2008, Microsoft announced Windows Server 2008 R2, as the server variant of Windows 7. Windows Server 2008 R2 will ship in 64-bit (x64 and Itanium) only.
Windows 7 is the current major release after Windows Vista and was planned for a three-year development timeframe. Microsoft’s main goal was to make Windows 7 more user centric and to focus on performance improvements. Some features of Windows 7 are faster booting, Device Stage, multi-touch, improved window management, home group networking, multiple thumbnails for combined taskbar buttons, and better power management for notebooks. Features included with Windows Vista and not in Windows 7 include the sidebar (although gadgets remain) and several programs that were removed in favor of downloading their Windows Live counterparts.