What is CPU scheduling and why is it necessary?

CPU scheduling determines which process gets to use the CPU at any given time from the ready queue. It's necessary because multiple processes compete for limited CPU time, and efficient scheduling maximizes CPU utilization, throughput, and responsiveness. The scheduler decides when to switch processes (preemptive) or waits for processes to yield (non-preemptive). Key metrics include turnaround time, waiting time, and response time.