In the beginning there was one version of windows, and it was a royal piece of (censored). (should probably add an IMHO here too). Then came version 2, and finally came version 3, which was the first one that actually worked well enough to be usable (again IMHO). It was the first really big seller for Microsoft, and you’ll find very few people these days who worked with any version of windows prior to 2, but you will find many who used 3.
Windows 3.0 was designed basically for a single user machine. 3.1 added some nifty enhancements to take advantage of the 386 processor (if you used 386 enhanced mode, it would still run in 286 mode). For business users, Microsoft made a version with a bunch of network support. I’m not sure what all the different versions were. The one I used was 3.51.
Then came Windows 95, which was a huge leap from 16 bit code to 386 code (not just the minimal 386 enhanced mode for windows 3.1, but a true 32 bit operating system). Despite the name change and the marketing hype, windows 95 identifies itself as windows 4.0.
In the mean time, Microsoft developed their next version for business and network users, and called this NT 4.0. One of the main problems that affected windows 3.x and windows 95 was stability. A misbehaving program could easily bring the entire computer to its knees. This was a bad thing for business users, who needed more stability. One of the major factors affecting stability was the fact that windows 95 was backwards compatible to DOS, and DOS allowed programs to directly access all of the computer’s hardware. In fact, DOS was such a minimal operating system that it didn’t manage the hardware at all, and programs were forced to directly access the hardware. The whole concept of device drivers wasn’t really there in DOS.
To get around the stability issues, NT 4.0 does not allow programs to directly access hardware. This is great for system stability, but royally stinks for backwards compatibility. This led to two different philosophies for the operating systems. If you needed stability (like business users) then you used NT 4.0. If you needed direct hardware access (good for games and backward compatibility) then you used 95.
Microsoft next released Windows 98, which identifies itself as windows 4.1. As you’d expect from the version numbers, it’s just a minor improvement to 95, taking advantage of newer hardware and integrating the web browser into the operating system.
Next came Windows 2000. By this time, Microsoft is getting tired of supporting two operating system lines, so they plan on everyone upgrading to 2000. The only problem is that 2000 is NT 5.0. It has a lot of great new features, but like NT 4.0 before it, it royally stinks for things that need direct hardware access and backwards compatibility. Games tend to run fairly poorly on it. Early testers figure this out, and Microsoft changes gears and starts pushing this as the successor to NT. They then come out with ME, which incorporates a lot of the new features of 2000 into the 9.x line. Remember, they would prefer to sell one operating system to everyone, so they start taking out parts of the 9.x series that they don’t think customers need any more, so that they are starting to “merge” their operating systems (merge actually means they want to kill off the 9.x line and force everyone to NT, which isn’t really a merge).
The next big thing from Microsoft is XP. This is supposed to be more significant of a change than from windows 3 to 95, if you believe the hype coming out of Microsoft. However, the operating system identifies itself is NT 5.1, which gives you a better clue what is really going on. The guts of the operating system don’t change much from 2000, but the user interface gets a huge facelift. This is also where they choose to “merge” the two operating systems, but remember this is still NT and it has all those things that are great for stability but royally stink at backwards compatibility. As you’d expect, it tends to suck royally at running DOS programs that do a lot of direct hardware access. However, during the time between the release of 2000 and XP, most new games have switched over to using DirectX (something that was starting to happen before 2000 was released), so most games and things that people use at home will actually run on XP.
The 9.x line is officially now dead, and we all run NT from here on out, whether we like it or not. If you have old DOS games, or software that only runs on 9.x type machines (like DOS based prom burners and other specialty type things) Microsoft doesn’t care about you.
In summary, prior to the relase of XP, there were two lines, the 9.x line and the NT line, and Microsoft of course expected you to buy the latest in whichever series you use. Now there is just XP, and they expect users of both 9.x and NT to upgrade to it. In a short time, expect 2000 and ME to drop off of the shelves, and all new computers will start shipping with XP.
Microsoft is currently on about a 2 year cycle. Expect the next big thing that is going to take over the world to be released around 2003 or 2004.