Scheduling (operating systems) is the fundamental operating system function responsible for determining which processes or threads are allocated access to system resources, primarily the central processing unit (CPU), and for how long. It involves implementing policies and algorithms to manage the execution of multiple competing demands for resources, aiming to optimize performance objectives such as maximizing throughput, minimizing response time, ensuring fairness among processes, and achieving efficient resource utilization. This concept is central to managing concurrency within a system and is a key component in the design and analysis of system performance, with principles extending to resource management in environments like distributed systems and often analyzed using models from queueing theory.