Explain Round Robin scheduling and its time quantum selection.

Round Robin assigns each process a fixed time slice (quantum). Processes execute for their quantum or until completion/blocking, then move to queue end. It's preemptive and fair. Time quantum selection is crucial: too small increases context switch overhead, too large becomes FCFS. Typical values: 10-100ms. Response time is good for interactive systems. Average waiting time can be high but no starvation. Used as base for modern schedulers.