Multitasking
Multitasking is the concurrent execution of multiple tasks (also known as processes) over a certain period of time
While a computer may be viewed as running one gigantic program stored in its main memory, in some systems it is necessary to give the appearance of running several programs simultaneously.
This is achieved by multitasking i.e. having the computer switch rapidly between running each program in turn.
In a time-sharing system, multiple human operators use the same processor as if it was dedicated to their use, while behind the scenes the computer is serving many users by multitasking their individual programs.
In multiprogramming systems, a task runs until it must wait for an external event or until the operating system's scheduler forcibly swaps the running task out of the CPU.
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.
Depending on the operating system, a task might be as large as an entire application program, or might be made up of smaller threads that carry out portions of the overall program.
Multiprocessing
Some computers are designed to distribute their work across several CPUs in a multiprocessing configuration.
Therefore Multiprocessing is the use of two or more central processing units (CPUs) within a single computer system.
Multiprocessor and multi-core (multiple CPUs on a single integrated circuit) personal and laptop computers are now widely available, and are being increasingly used in lower-end markets as a result.
