A single-user operating system is a type of operating system (OS) that is developed and intended for use on a computer or similar machine that will only have a single user at any given time. This is the most common type of OS used on a home computer, as well as on computers in offices and other work environments. There are two general types of single-user operating system: single task and multitasking systems. Though a single-user operating system can be connected to other systems through a network, it is still truly only used by a single person and is different than a multi-user OS.

The operating system installed onto a computer is responsible for handling a number of different tasks and is typically one of the most important programs used on a computer. An operating system manages memory usage and other resources, as well as hardware connectivity and the proper execution of other applications. There are several different types of operating systems, but the single-user operating system is typically the most common.

A single-user operating system that is a single task system is developed for use with a computer or electronic device that will only run one application at a time. This type of OS is typically used on devices such as wireless phones and two-way messaging devices. A single task, single-user operating system can only run one program or application at a time, and so is not as useful for a computer or other device intended to run multiple programs at once.

This is where a multitasking single-user operating system is used instead. A multitasking OS can run multiple applications and programs at once. This is often used on computers where someone may wish to navigate the Internet, run a graphics editing program, play music through a media playing program, and type in notes in a simple word processing program all simultaneously. A single task OS could not do this, but the multitasking systems are able to handle all of these processes.

Even though a single-user operating system can connect to other computers and systems through a network, it is still only being used by a single user. As long as the computer only has one monitor, keyboard and other input devices, then it is a single-user system. Other computers may be able to access data on the computer, but unless the users of those computers can also run applications on the computer that they see on monitors on their own end, it is still a single-user system.