An interrupt is an asynchronous signal indicating the need for attention or a synchronous event in software indicating the need for a change in execution. Type • Hardware interrupt Causes the processor to save its state of execution and begin execution of an interrupt handler. o Mask able o Non mask able o Inter processor interrupts • Software interrupts Are usually implemented as instructions in the instruction set, which cause a context switch to an interrupt handler similar to a hardware interrupt. 1. Maskable interrupt (IRQ) is a hardware interrupt that may be ignored by setting a bit in an interrupt mask register's (IMR) bit-mask. 2. Non-maskable interrupt (NMI) is a hardware interrupt that lacks an associated bit-mask, so that it can never be ignored. NMIs are often used for timers, especially watchdog timers. 3. Inter-processor interrupt (IPI) is a special case of interrupt that is generated by one processor to interrupt another processor in a multiprocessor system. 4. Software interrupt is an interrupt generated within a processor by executing an instruction. Software interrupts are often used to implement system calls because they implement a subroutine call with a CPU ring level change. 5. Spurious interrupt is a hardware interrupt that is unwanted. They are typically generated by system conditions such as electrical interference on an interrupt line or through incorrectly designed hardware. Source- wiki and google search