A signal is a way to send information using electronic equipment. Signals can be electrical or electromagnetic currents that carry data between systems or networks. In electronics, signals are often changing voltages or electromagnetic waves that carry information. There are two main types of signals: analog and digital.
Analog signals change over time and can have any value within a certain range, like voltage or current. They use properties of the medium, like electricity flowing through a wire, to convey information. Analog signals can represent things like light, sound, temperature, position, and pressure.
Digital signals, on the other hand, represent data as specific values from a set of options. They can only have certain values at any given time. The physical representation of the information in a digital signal can be things like electric current, voltage, electromagnetic properties, or sound pressure. Digital signals are commonly used in electronics, computers, and devices that transmit data.
In a signal circuit, an electric circuit powers the signaling equipment. Examples of signaling equipment include doorbells, chimes, code-calling systems, signal lights, and buzzers.