Microsoft created their monopoly through exclusivity contracts. Those contracts were effectively the death of IBM OS/2 and HP NewWave. Those contracts are also what held Linux adoption back. That's not to say that OS/2 or NewWave would still exist or Linux adoption would be higher now without those exclusivity contracts, but the contracts certainly didn't help matters and did in fact create a monopoly for MS in the OEM PC market. Windows is the only truly unique operating system. Almost everything else is either based on Unix, BSD or Linux. Outside of Windows, the options are mind-numbing. Not all Linux distros are created equal, which makes choosing one quite difficult. MacOS is the most user-friendly BSD based OS. Apple can only copyright and patents the things they do now, because US Patent and Copyright laws were changed. When Apple filed against MS over the GUI, you had to prove the existence of a unique product to receive a patent or copyright for it. Under the current laws, you can simply patent an idea. There is no requirement for the idea to even be unique or for the idea to ever result in a functional product of any type. This is called "Proof of Concept"....which used to be a temporary patent to allow you time to develop and patent the product. Now "Proof of Concept" patents work the same as product patents. Technically, Microsoft does still control the PC OS market. But, you're right. Far from being a monopoly now. On OEM products you have a choice of Windows, MacOS, iOS, FireOS, Android, ChromeOS and Ubuntu Touch. That's without getting into custom built PC's and laptops. Obviously I'm taking into account tablets and smartphones, as they are computing devices. Thanks to Amazon, Google and Canonical, Linux is actually the dominant OS kernel, not taking device type into account. Windows has fallen to second place in the global OS market. With or without Microsoft, there would be an OS that's dominant on each platform. A market can only sustain but so many competing products. The dominant OS on any platform is going to be the OS that offers the most flexibility. That's part of the reason Android has almost completely dominated the smartphone market. It's the most flexible mobile OS. If Google handles ChromeOS properly in the future, it has the potential to overtake Windows on the PC. Obviously that's not going to happen in the short term, but with the trend going so heavily towards mobile it's possible we could see a shift from Windows to ChromeOS over the next 10 years. It's just a matter of pricing for Chromebooks.