Schedulers are specialised computer programs that govern how processes are scheduled in various ways. Their primary responsibility is to determine which jobs should be entered into the system and which processes should be carried out.

The following are the three types of schedulers:

• Long Term Scheduler: A long term scheduler is ALSO KNOWN as a task scheduler. A long-term scheduler determines which applications are accepted for processing into the system. Before executing a process, it selects it from the ready queue and loads it into memory. For CPU scheduling, the process is loaded into memory. The job scheduler's primary goal is to deliver a well-balanced MIX of operations, including input/output and CPU-bound workloads. It also regulates how much multiprogramming is done. If the degree of multiprogramming remains constant, the average rate of process formation must be equal to the average rate of process departure from the system.
• Medium Term Scheduler: The medium-term scheduler is used to shift programs in the main memory. It frees up RAM that has been consumed by the processes. As a result, multiprogramming is reduced to a minimum. The SWAPPED out processes are managed by the medium-term scheduler.
• Short Term Scheduler: A short term scheduler is also known as a CPU scheduler. Its primary goal is to improve system PERFORMANCE in accordance with a set of predetermined criteria. It is the transition of a process from the ready to the operating state. The CPU scheduler picks one of the ready-to-run processes and allocates CPU time to it. Short term schedulers, often known as dispatchers, choose the next process to run.