In computing, the concept of completion by executing multiple tasks simultaneously in a given time period is called 'multitasking'.
Many tasks need to be done on the computer in support of each other.These functions can be stored in memory at once, and the operating system determines which program to process for how long and when to go to the next program for processing.
Multitasking automatically interrupts the running program, saving its state (partial results, memory contents and computer register contents) and loading the saved state of another program and transferring control to it.
Multitasking does not require parallel execution of multiple tasks at exactly the same time; instead, it allows more than one task to advance over a given period of time. Even on multiprocessor computers, multitasking allows many more tasks to be run than there are CPUs.
Example: If you are creating a word document while listening to songs on your computer and simultaneously the software download from the internet is running in the background, it means that your computer is 'multitasking' for you.