Multi-user - Definition and Overview

Multi-user operating systems allow multiple users to utilise the computer and run programs at the same time. All time-sharing systems are multi-user systems, but most batch processing systems for mainframes were too, to avoid leaving the expensive CPU idle while it waited for I/O operations to complete.

The most obvious example is a Unix server where multiple remote users have access (via Telnet) to the Unix shell prompt at the same time.