Operating Systems

An Operating System is the "interface" between software applications and computer hardware, there are different sorts and types of operating system and don't forget a mobile phone has an operating system, which is very clear with modern smart phones.

Windows

Windows Server and Microsoft Windows and Windows Phone 8

Linux

Linux

Android

Android

Unix

Unix

ReactOS

This is an interesting project! It is something I would like to study more, in a VM in VirtualBox of course. The team are building an Open Source, Windows compatible operating system called ReactOS, ReactOS Project and it does look very promising.