CPU scheduling is the basis of multi-programmed operating systems. By switching the CPU among processes, the operating system can make the computer more productive.

The idea of multiprogramming is relatively simple. Whenever the CPU becomes idle, the operating system must select one of the processes in the ready queue to be executed. The selection process is carried out by the short-term scheduler. The scheduler selects from among the processes in memory that are ready to execute, and allocates the CPU to one of them. CPU scheduling deals with the problem of deciding which of the processes in the ready queue is to be allocated the CPU.

Note: There are many types of scheduling algorithms.