A scheduling algorithm is a strategy used to pick a ready task for execution. A round robin scheduler has the ability to stop a process in the middle of execution, so it is a non-preemptive scheduler.
One way we can judge a scheduler is by its average response time, in which we want to minimize the average tmie that a job waits in the ready queue before it gets scheduled.
First-come-first-serve does not achieve this goal (counterexample is a large first process).
Other scheduling algorithms are just in CS 4820.