FCFS stands for First Come First Serve, which is an operating system scheduling algorithm that automatically executes queued requests and processes in order of their arrival. In this algorithm, the job that arrived first in the ready queue is allocated to the CPU first. FCFS is a simple and easy-to-understand scheduling algorithm that does not require complex computations or heuristics. It follows the non-preemptive approach, which means that once a process has control over the CPU, it will continue to run until it completes its CPU burst or voluntarily relinquishes the CPU. FCFS uses a simple queue structure to manage the order in which processes are scheduled. However, FCFS has limited scheduling flexibility, as it does not take into account the priority or resource requirements of the processes, which can lead to suboptimal performance in certain scenarios. FCFS is not optimal for interactive systems, as it may cause long waiting times for users, leading to a poor user experience.