The volt is the SI unit of electric potential difference.
A potential difference of one volt means that one joule of energy is transferred per coulomb of charge. In symbols, 1 V = 1 J/C. Voltage describes the energy difference that can drive charge through a circuit; it does not by itself specify how much current flows.
The unit is named after Italian physicist Alessandro Volta, whose work on electrical cells contributed to early battery technology. A battery’s voltage is often described as its electromotive force, although real batteries can have terminal voltages that change with current, load, and state of charge.
Voltage, current, and resistance are related in many simple circuits by Ohm’s law, but they are different quantities. Voltage is measured with a voltmeter, which is connected in parallel so it compares the potential at two points.