Final answer:
The power button in a system is used to turn the system on and off.
Step-by-step explanation:
The power button in a system typically serves to turn the system on and off. It is a hardware button that provides the functionality to control the power state of a computer or electronic device. When pressed, it initiates the boot-up sequence and powers on the system, allowing it to start running. Conversely, pressing the power button again when the system is on initiate the shutdown process and turns off the system.