The telegraph is made up of a telegraph key, or the sender, and a receiver.
Wires connect the sender and the receiver.
As a telegraph key is moved up and down, it makes or breaks an electric circuit and transmits a signal as a series of electric pulses. In the telegraph's simplest form, an electromagnet in the receiver is activated by alternately making and breaking the circuit. Reception by sound, with the Morse Code signals received as audible clicks, was the basis for a low-cost, reliable method of signaling. The telegraph spread across the country rapidly. Only seventeen years after the first telegraph was put into place, the telegraph had spread its wires from California to New York.