The kernel is the heart of the operating system. Controls the hardware.
Turns parts of the computer system on and off at a programs command.
A program that connects and interprets the commands typed by user. It interprets user requests, calls programs from memory, and executes them one at a time or in a series called ‘pipe’. Bourne shell & C shell comes with UNIX system.
Tools and Applications
The applications and utility layer in Unix includes the word processors, graphics programs, database management programs, commands etc. The application programs provide an application to the end users.