A voltmeter is an instrument used to measure the electrical potential difference, or voltage, between two points in an electrical circuit. It is typically connected in parallel with the component or section of the circuit being tested. Voltmeters can be analog, using a needle and scale, or digital, displaying readings on a screen. Voltmeters are essential tools in electronics and electrical engineering, helping to diagnose issues and ensure circuits operate within safe voltage levels. They can measure both direct current (DC) and alternating current (AC) voltages, making them versatile for various applications, from household appliances to complex industrial systems.