A multivibrator is an electronic circuit that can generate a continuous square wave signal. It typically consists of transistors, resistors, and capacitors, and is used in various applications such as timers, oscillators, and flip-flops. There are three main types of multivibrators: astable, monostable, and bistable, each serving different purposes in electronic devices. Astable multivibrators continuously switch between two states, creating a square wave output. Monostable multivibrators have one stable state and produce a single output pulse when triggered. Bistable multivibrators, also known as flip-flops, can store binary information, making them essential in digital circuits and memory devices like RAM and registers.