(1) For the messaging app, see
Signal messaging app.
(2) A pulse or frequency of electricity or light. A signal can be transmitted in a wire, by fiber or wireless. The term is generic and may refer to virtually anything generated and transmitted, including data, control signals and the pulses in an electronic circuit. The term is often used with another word, such as "carrier signal," "data signal" or "control signal." See
signal-to-noise ratio and
control signal.
Signal vs. Signaling
A "signal" can refer to data or a control signal, but "signaling" refers to transmitting only control signals. It is very common to hear the term in the telecom industry, where "signaling" means setting up and breaking down a call, but does not refer to the actual pulses or frequencies of the data (voice, text, etc.) itself (see
SS7 and
signaling).