CPU Scheduling in Operating System

CPU scheduling is a process which allows one process to use the CPU while the execution of another process is on hold(in waiting state) due to unavailability of any resource like I/O etc, thereby making full use of CPU. The aim of CPU scheduling is to make the system efficient, fast and fair. 

Who - Short term scheduler 
Where - Ready state to running
When - when a process move form
    
        1) Run - Termination
            Run - Wait
            Run - Ready

        2) New - Ready i.e When a processes is just created

        3) Wait - Ready