In this post I want to briefly talk about Android (mobile phone OS, and applications).
First of all, it is not right to call it Android OS, as the operating system in Android phones and devices is not actually "Android". The operating system is Linux, which is an open-source operating system. For the same reason, the operating system that you see on different Android devices are not actually the same (at least in terms of looks)! And the reason for that is that each of the companies change the OS the way they want. For example, the OS in android devices that Sony makes look quite different than the ones created by Samsung. Furthermore, the operating system on Android devices is written in C language rather than Android langugage (just like Linux distros).
They why do they even call these "Android"? The second point is that Android is actually built on top of Java. Android applications are actually in written a language with the same exact syntax with Java with a difference that Android apps use their own libraries (namely Android libraries), so in some sense, they are somehow different from Java (which is why they gave them a new name, Android!).