New tasks can interrupt already started ones before they finish, instead of waiting for them to end. As a result, a computer executes segments of multiple tasks in an interleaved manner, while the tasks share common processing resources such as central processing units (CPUs) and main memory.
Multitasking is a common feature of computer operating systems. It allows more efficient use of the computer hardware; where a program is waiting for some external event such as user input or an input/output transfer with a peripheral to complete, the central processor can still be used with another program.
Example of usage – “Often multitasking operating systems include measures to change the priority of individual tasks so that important jobs receive more processor time than those considered less significant.”