An embedded operating system is a specialized OS for use in the computers built into larger systems.
An embedded system is a computer that is part of a different kind of machine. Examples include computers in cars, traffic lights, digital televisions, ATMs, airplane controls, point of sale (POS) terminals, digital cameras, GPS navigation systems, elevators, digital media receivers and smart meters, among many other possibilities.
In contrast to an operating system for a general-purpose computer, an embedded operating system is typically quite limited in terms of function – depending on the device in question, the system may only run a single application. However, that single application is crucial to the device’s operation, so an embedded OS must be reliable and able to run with constraints on memory, size and processing power.
See a video introduction to embedded operating systems: