Telegraph is a system that uses a wire to send messages over vast distances, particularly one that generates signals by connecting and disconnecting electrically. Two key pieces of hardware defined the telegraph. The first was the transmitter, also called the key. The operator of this instrument tapped out messages composed of dots and dashes by alternately closing (pressing the key) and breaking (releasing it) an electrical circuit. A quick tap created a dot, while holding the key down for three times as long created a dash.