What causes an interrupt handler to run?

An interrupt handler runs in response to an interrupt signal generated by hardware or software events, such as input from a keyboard, mouse, or network device. When an interrupt occurs, the processor temporarily halts its current execution, saves its state, and transfers control to the designated interrupt handler, which addresses the specific event. Once the handler completes its task, the processor can resume its previous operations. This mechanism allows systems to respond promptly to asynchronous events.