A voltmeter is a device used to measure the voltage or electric potential difference between two points in an electrical circuit. Voltage, often denoted by the symbol "V" and measured in volts (V), represents the potential energy difference per unit charge between those two points. In simpler terms, it tells you how much energy each unit of electric charge would gain or lose when moving between the two points.
Voltmeters are commonly used in various applications, such as testing and troubleshooting electrical circuits, monitoring batteries, and measuring the output of power sources. They are connected in parallel across the points where the voltage is to be measured, and they display the numerical value of the voltage on their display panel or screen.