Multiuser operating system

Some operating systems, in addition to being able to run multiple programs at the same time with multitasking technology, allow multiple users to sue an application simultaneously. These are known as multiuser operating systems.

In a modern multiuser operating system, a number of users located at different terminals run the same or different programs.

Multiuser operating systems are similar to many other types of operating systems. A multiuser system is almost by definition also multitasking system. On the other hand, multitasking typically refers to systems in which the tasks interact, while multiuser systems generally try to isolate the various tasks.

Most multiuser systems use preemptive, multitasking technology. A multiuser operating system must determine how to divide processor time among competing users. Various scheduling method determine which user is given access to the processor at a particular time.

When a multiuser operating system is well designed and it is running on a computer that is not overloaded, each individual user may indeed think that he has the computer all to himself. The multiuser operating system is a complex program, and requires space and time overhead.
Multiuser operating system