Yours, Etc.: Origins and Uses of 8 Sign-Offs
(Or "time quantum", "quantum") The period of time for which a process is allowed to run uninterrupted in a pre-emptive multitasking operating system.
The scheduler is run once every time slice to choose the next process to run. If the time slice is too short then the scheduler will consume too much processing time but if it is too long then processes may not be able to respond to external events quickly enough.