Flip-flop is a circuit which can be turned on and off with the same signal. It is like a single switch button when the first time you press it turns on and when second time you press it turns off. So like flip means turn on and flop means turn off. A flip-flop is a sequential logic device. Flip-flop has two states it may be high (or 1) or low (or 0), So flip-flop is called bistable device. There are different types of flip-flop like SR flip-flop, D flip-flop, JK flip-flop, SR flip-flop, master-slave flip-flop etc.