A monopolistic operating system that only exists in the 2010's because of the IBM-linked historical lock-in and constant useless changes of the Microsoft Word document format to prevent cross operability.
The following anecdote illustrates Windows' pervasiveness. Ciro Santilli was once tutoring a high school student in Brazil, and decided to try and get her into programming. When the "Windows is not free" subject came up, the high school student was shocked: "I paid 100 dollars for this?". She never even knew it was there. To her, it was "just a computer".
Laws should really be passed forcing OEMs to allow you to not buy Microsoft Windows when buying a computer, European Union, why have you failed me in 2016??? https://en.wikipedia.org/wiki/Bundling_of_Microsoft_Windows
http://blog.zorinaq.com/i-contribute-to-the-windows-kernel-we-are-slower-than-other-oper/ I Contribute to the Windows Kernel. We Are Slower Than Other Operating Systems. Here Is Why. by Marc Bevand (2013) has some interesting remarks:
There's also little incentive to create changes in the first place. On linux-kernel, if you improve the performance of directory traversal by a consistent 5%, you're praised and thanked. Here, if you do that and you're not on the object manager team, then even if you do get your code past the Ob owners and into the tree, your own management doesn't care. Yes, making a massive improvement will get you noticed by senior people and could be a boon for your career, but the improvement has to be very large to attract that kind of attention.