A relay is an electrically operated switch. It allows a low-power circuit to control a higher power circuit by using an electromagnet. The 12V DC relay is powered by a 12-volt direct current (DC) source, commonly found in automotive systems, microcontroller projects, and other low-voltage applications. It consists of a coil, armature, spring, and one or more sets of contacts. When current flows through the coil, it creates a magnetic field that pulls the armature towards the coil, closing or opening the contacts, depending on the relay's design.

    Relays can be categorized into different types, such as single-pole, double-throw (SPDT), and double-pole, double-throw (DPDT), depending on the number of contacts and how they switch. In the case of a 12V DC relay, the coil operates at 12 volts, and the contacts can switch currents typically ranging from a few milliamps to several amps.