A real-time system is a computer system that requires "correct" computing results within a specific period of the time. The results produced after that deadline are neglected, even if correct because they don't remain to have real value.

There are many examples in our daily routine where real-time systems are found like in domestic appliances like microwaves, ovens, and dishwashers, etc., in consumer digital devices like cameras and MP3 players. Our daily communication devices like cellphones and Android devices are also based on RTOS. They are also present in larger applications, such as automobiles and airplanes.

The figure below shows the basic structure of the real-time operating system in which the RT system placed in between operator (human interface) and controlled object i.e. instrumentation interface like sensors, actuators, etc.