Unix is a multiuser, multitasking operating system. It is the glue that holds together the various parts of a computer: memory, processor, disks, etc. Unix by itself is not a single operating system but a term that includes dozens of different implementations commonly referred to as Unix flavors.
Unix was designed to provide simple and flexible, yet powerful tools to perform a wide variety of tasks.
Basically a Unix operating system is made up by three pieces:
- The kernel is the core (the heart) of the system that sits in memory and controls computer resources.
- The shell that interacts with the user and the kernel. Interprets and executes commands.
- The applications that run on top of the shell.