A signal informing a program that an event has occured. When an interrupt is received the program stops normal execution and starts handling the interrupt by doing some special actions. There are two kinds of interrupts:
- Hardware: e.g. a user types something on a keyboard, the program has to process the input of the user and act apropriately
- Software: (also called an exception) e.g. when a program calls the operating system to do some disk I/O.