When Interrupt service routine is executed by a microprocessor?

An Interrupt Service Routine (ISR) is executed by a microprocessor when an interrupt signal is received, indicating that a specific event requires immediate attention. The microprocessor pauses its current execution, saves the state of the interrupted task, and transfers control to the ISR to handle the interrupt. Once the ISR has completed its task, the microprocessor restores the saved state and resumes execution of the interrupted task. This mechanism allows for efficient handling of asynchronous events in real-time systems.