&gt; If Microsoft ever released the Windows source code, what would we find? Simplicity?<p>Depends on where you look. Much of the NT kernel is &quot;simple&quot;, but it&#x27;s not easy stuff to get right. There&#x27;s a bunch of legacy code in the Win32 layers, especially dealing with user input, that is just frightening (comments like &quot;This stupid hack makes the utterly broken Compaq XYZ-3000 keyboard not crash the system&quot;). The COM stuff is just complex and arcane and top-heavy with architecture astronautics. The build system is, or was, a soul-destroying, radioactive and rotting cesspool of Perl; doing Windows builds sucked real hard.<p>So it&#x27;s a mix of really quite good code, and really quite awful code (that they&#x27;re dealing with, I think), and code that makes you want to quit, every day.<p>(Soapbox: You should <i>never</i> have code in your project that you are scared of touching. Never. If you do, get rid of it and replace it. Don&#x27;t layer over it, don&#x27;t give it to some intern to maintain, just face the problem and deal with it, or it will be the most costly code in your product).