Microsoft Windows is one of the most popular operating systems in use today. It is based around the idea of a graphical user interface, as opposed to a command line interface. This is not a new system, it has a history stretching back some twenty years.
The first development on Windows began in September of 1981. They were still calling it Interface Manager back then, and it bore little resemblance to today's Windows (or even to the finished Windows 1.0). By 1983 they had changed the name to Windows, and finally made a product announcement. But this announcement came only after VisiCorp (the makers of VisiCalc, which was a killer app for its time), released VisiOn, which was another operating environment designed to run on top of DOS.
Windows version 1.0 finally shipped on November 20, 1985. It did not exactly take the computing world by storm, as it faced heavy competition in the form of TopView, VisiOn, GEM, and DESQview (all of which beat Windows to market). The situation was not helped when Apple threatened Microsoft with a lawsuit over infringements on Apple's copyrights. Microsoft and Apple finally came to a licensing agreement that they were both happy with (Microsoft ended up getting the better deal because the contract allowed for the use of Apple's features in all future Microsoft products).
The initial Windows release (version 1.01), required MSDOS 2.0, 256K of RAM, 2 double-sided disk drives or a hard drive, and a Graphics-adapter card. Later versions increased the memory requirement to 320K, but the other system requirements remained unchanged, Windows shipped with a small selection of native applications, many of which still exist today in one format or another. This package consisted of MS-DOS Executive (the file manager), Calendar, Cardfile, Notepad, Terminal, Calculator, Clock, Reversi, Control Panel, PIF Editor, Print Spooler, Clipboard, RAMDrive, Windows Write, and Windows Paint. This was about all prospective Windows users had to work with, since third party Windows software was almost non-existent.
The interface itself was somewhat similar to that of the Macintosh (or of modern day Windows). It included pull down menus, and allowed more than one application to run by placing them in separate windows. But the "windows" could not overlap each other. They had to be "tiled" on the screen, which made them of limited use on the low resolution displays of the mid 1980s.
The system itself gained very little market share until Aldus PageMaker shipped in January of 1987 with a Windows executable. This was the first WYSIWYG desktop publishing program available on the PC platform, and finally gave people a reason to buy Windows. Later Windows compatible products included Excel and Corel Draw. But the system as a whole still needed work, and development on Windows 2.0 had already begun.
Windows 2.0 shipped in November of 1987. This version significantly changed the user interface. This new version included icons and windows that could overlap. Major applications were finally being developed for Windows. Microsoft even included a special "run-time version" of Windows with the new versions of Word and Excel. This special version would launch Windows to run the application, and then return back to the DOS prompt when the application was closed.
Microsoft later improved their design by optimizing it for the 386 processor (and renaming the original Windows 2.0 to Windows/286). This allowed the user to multitask DOS programs. This (along with a few other changes to the operating system) prompted Apple to take them to court for copyright infringement. But Microsoft won this case due to their earlier contract with Apple, and the fact that Apple stole a few of their ideas from Xerox in the first place.
Windows 3.0 was shipped on May 22, 1990. This was the first Windows release that was truly ready for the big time. It is plagued by a few stability problems, but the new features (and deals with vendors), caused this version to immediately gain marketplace dominance. New features included the Program Manager, File Manager, a better icon system, native 16 color support, and vastly superior hardware support. Third party developers finally started making Windows compatible programs on a vast scale. Over three million copies of Windows 3.0 were sold in the first year alone.
Windows 3.1 was released in April of 1992 and was a vast improvement over the already popular Windows 3.0. This version added Truetype font support, multimedia capabilities, and object linking and embedding. This version upped the hardware requirements a bit. System requirements included; a 286 processor, 1 MB RAM, a 6 MB hard drive, and an EGA or better video card. But that was only the minimum requirements. The recommended setup was a 386 processor, 3 MB RAM, a 10 MB hard drive, a mouse, and an SVGA video card.
Windows 3.1 remained the most common PC operating system until well into 1997 when Windows 95 finally overtook it on the desktop. This is probably the oldest Microsoft operating system that is still in regular use anywhere today.
Windows 3.11 was later released as a bug fix version, and was available as a free upgrade from ftp.microsoft.com
Windows for Workgroups
Windows for Workgroups shipped on October 27, 1992. It was based on Windows 3.1 but included integrated networking capabilities including file sharing, e-mail, and group scheduling. This version did not take off commercially as Microsoft planned, and it was soon replaced with the Windows NT line of products.
Windows NT was the first version of Windows that was truly a stand alone operating system (it did not just run on top of DOS like all previous, and several later Windows versions did).
The first version of NT was Windows NT 3.1. The version number was selected to make it appear as if it was a continuation of the already successful Windows 3.x line (choosing to make a superior product appear to be based on an older one must have been a marketing decision). This version was shipped on May 24, 1993, and had a user interface very similar to the Windows 3.x line (marketing again). This was the first version to support the superior Win32 API (which fully utilized the 32 bit capabilities of 386 and higher hardware),, but it suffered from hardware incompatibilities, and required a rather high end computer to run.
Windows NT 3.5 was released in 1994 and vastly improved compatibility, memory handling and introduced OLE 2.0. There are still a lot of old NT 3.5 servers around today, the same cannot be said for the NT 3.1 release.
Windows NT 4.0 shipped in July of 1996, and some people still claim that this is Microsoft's best operating system to date, This version used the new friendlier Windows 95 interface, and vastly improved on the NT 3.5 design in almost every category. Microsoft saw this system as a replacement for Unix and included many of the features that the corporate sector demanded.
Microsoft continued to improve NT 4.0 with several service packs, and many people still use this operating system even today. Many people still demand Windows NT today, because of its stability and feature set. Windows NT eventually gave way to Windows 2000 and Windows XP, but it still has a huge install base all across the world.
Windows 95 was launched on August 24, 1995. This was the single largest advance ever for the Windows product line. This was a 32 bit system and featured pre-emptive multitasking, networking, threading, and finally featured an interface that could rival that of the Macintosh. Although the system featured nothing completely new, it was definitely the most polished thing to come out of Microsoft's doors to date.
Windows 95 featured support for a wide variety of hardware (and eventually supported more hardware than any other operating system before or after). Users of Windows 95 could run MSDOS, Windows 3.x, and Win32 programs side by side in the friendliest Microsoft GUI to date. Windows 95 was so user friendly that normal people final began using PCs on a regular basis. It could even be argued that Windows 95 is what truly started the big boom in the computer industry.
However, Windows 95 was based on a lot of legacy code (and this situation got worse as the Windows 9x product line progressed). It managed to nicely hide its DOS and Windows 3.1 underpinnings from the average user, but programmers and power users alike learned that Windows 95 came with a lot of limitations due to its backward compatibility with DOS and Windows 3.x.
The last version of Windows 95 shipped in October of 1996 (OSR2), and included many improvements and several of the features that would later be integrated into Windows 98. Many people still contend that Windows 95 OSR2 was the best release in the Windows 9x line (and I tend to agree with them).
Windows 95 still has a huge install base all over the world, and will probably continue to for years to come. Microsoft has finally begun to try and phase out this system by not releasing updates for it anymore, for example, the latest versions of DirectX and Windows Media Player are only available for Windows 98 and above. But it is going to take more than that to phase out the huge corporate and consumer install base of this operating system (and third party developers still continue to crank out applications that are compatible with Windows 95).
Windows 98 was first shipped on June 25, 1998. It featured numerous bug fixes to Windows 95 (and a few new ones of its own), and integrated Internet Explorer into the operating system (although it was later shown that IE can be removed with a bit of hacking).
The user interface saw many cosmetic changes (although usability didn't really change), and minor internal changes including a new kernel and integration of DirectX. Brand new Windows 98 features included multiple monitor support (which was the "killer app" for me, and was the reason I upgraded), DVD, AGP, and USB support, and a whole host of other minor improvements. The downside of all this was a slight decrease in overall system stability, which was worsened by using the Active Desktop feature (which allowed you to imbed web pages in your desktop).
Windows 98SE (Second Edition) was released in 1999 and fixed many of problems with the initial release of Windows 98. New features were sparse, but included internet connection sharing (which allowed several PCs to easily share one internet connection on a LAN). Most gamers will argue that this was the best Windows release to date, and for gaming it probably is.
Windows 2000 shipped on February 17, 2000. This was the successor to Windows NT 4.0. It was a vast improvement in usability, features, security, and (a few patches later), stability over all previous Microsoft operating systems. It seems that Microsoft took everything that was good about Windows NT, and combined it with most of the good stuff from Windows 98, added in a new interface and some advanced (but user friendly), networking capabilities to come up with Windows 2000. This is first operating system ever that could rival Unix in the server room, Windows 98 in the gaming arena, and Macintosh on the desktop (note, I did say "Rival", I did not say "defeat").
Windows 2000 had a new user interface (still familiar looking, but new), and supported several things that the Windows NT line did not, such as DirectX and USB (well technically one of the Service Packs added USB support to Windows NT, but it wasn't full support). File sharing, encryption, permissions, general networking capabilities were the best that Microsoft had ever offered.
The only real problems with Windows 2000 were the large install size, lack of security compared to Unix, and a few problems running some Win9x software (it did not have the "full compatibility" that it was supposed to). This is still the Windows version of choice for many people, and has a large install base (but not as large as Windows 9x does).
Windows ME (Millennium Edition) debuted on September 14, 2000. This was not a major upgrade as previous versions had been. It did offer some new multimedia and system restore capabilities (and a slightly prettier interface). But many people argued that all that came at the expense of stability, and that the new features were not very useful. Windows ME probably has a smaller user base than any other version of the Windows 9x line (despite being the newest). Many people actually went back to Windows 98 after using ME for a while (I certainly did).
Windows XP was launched on October 25, 2001. This Windows has finally merged the divergent Windows code base (NT/9x), into a single operating system. Windows XP is available in five versions designed to completely replace all previous Microsoft operating systems. The versions are; Home Edition (replaces Win9x), and Professional, Server, Advanced Server, and Datacenter Server to replace the Windows 2000 product line (no mention of the fairly unpopular Terminal Server, which may have been discontinued).
Under the hood Windows XP is based on the Windows NT/2000 code base, but has had a lot of improvements which allow for a large variety of software to run properly (including a new dll system that allows multiple versions of dlls to be used for different applications). Users can set version compatibility for various applications to fool them into thinking they are running on a previous Windows version. This was a problem with Windows 2000, as many programs that could technically run under 2000 would detect the NT kernel and abort themselves (games for the most part).
Windows XP comes packed with new utilities and includes an all-new user interface called Luna. The new interface has drawn quite a lot of flack, both for its simplicity, and for its similarity to the Aqua interface in Mac OS X. But the interface is skinnable, and can even be set to look more like the Windows 98 you may be used to.
Finally, Microsoft has built Digital Rights Management right into the operating system (along with the now expected Internet Explorer and Windows Media Player). Digital Rights Management (which relates to the ability to copy and play back media files), has caused a bit of an uproar among some users. But Microsoft ended up scaling it back a bit before the final XP release.
Feel free to /msg me if I have missed something (like Windows Vista).