The operating system is made of three parts:
A user executes programs. AngryBird is a program that gets executed by the kernel, for example. When a program is launched, it creates processes. Program or process will be used interchangeably.
The Kernel handles the main work of an operating system:
A user interacts with the Kernel via the Shell. The console as opened in the previous slide is the shell. A user writes instructions in the shell to execute commands. Shell is also a program that keeps asking you to type the name of other programs to run.