In the electronics world, a flip-flop is a type of circuit that has two states (i.e. on or off, 1 or 0) and are often used to store state information. By sending a signal to the flip-flop, the state can be changed. Flip-flops are used in a number of electronics, including computers and communications equipment.
The first flip-flop was built by William Eccles and F.W. Jordan in 1918 and called the Eccles-Jordan trigger circuit. The common term "trigger circuit" or "multivibrator" was used to describe the earlier flip-flops, which were two-state circuits. While basic in design, there were multiple varieties of these flip-flops: astable multivibrator, monostable multivibrator and bistable multivibrator. The latter variety was typical known as a flip-flop. Over time, there were a number of types of flip-flops developed, including D flip-flop, T flip-flop, and JK flip-flop.