There are three types of scheduler in Operating system.
1. Long term scheduler (LTS)
LTS or Job scheduler, LTS is responsible for creating new processes and bringing them into the system.
LTS is responsible to switch the processes to the ready state from new state, that is the reason LTS also known as job scheduler.
2. Short term scheduler
Short term scheduler or CPU scheduler is responsible for scheduling one of the process from ready state to the running state.
Short term scheduler responsible to allocated the CPU to the process , than switches that process from ready state to the running state.
Short term scheduler allocated the CPU so it’s also known as CPU scheduler.
3. Medium term scheduler
Is responsible of suspending and resuming the processes.The medium term scheduler is also known as swapper.
Medium term scheduler is responsible for switching the process from ready state and wait state to the suspended ready state and suspended wait state.
To know about suspend ready and suspend wait state click here.