A voltmeter, also known as a voltage meter, is an instrument used to measure the potential difference, or voltage, between two points in an electrical or electronic circuit. Some voltmeters are intended for use in direct current (DC) circuits; others are designed for alternating current (AC) circuits. Specialized voltmeters can measure radio frequency (RF) voltage.
Measurements are made on a scale normally graduated in millivolts (0.001 volts), volts or kilovolts (1,000 volts).