What is Operating System?

Operating system is a computer program that manages computer hardware and software resources, and is also the core and cornerstone of computer system.The main functions of operating system are to manage and configure memory, determine the priority of system resources supply and demand, control input and output devices, operate network and manage file system.

And write sevral your familiar operating systems in details.

Linux

Linux is a set of free-to-use and free-to-spread Unix-like operating system. It is a multi-user, multi-task, multi-threaded and multi-CPU operating system based on POSIX and UNIX.