what does a voltmeter measure

A voltmeter is an instrument used for measuring the voltage or potential difference between two points of an electronic or electrical circuit. It measures the difference between the positive input of voltage and the negative input of voltage. A voltmeter is connected in parallel with the circuit, mainly because the same voltage drop occurs across it. It usually has a high resistance so that it takes very little current from the circuit being measured. Voltmeters are made in a wide range of styles, some separately powered (e.g. by battery), and others powered by the measured voltage source itself. They are used to measure voltages usually calibrated in volts, millivolts (0.001 volt), or kilovolts (1,000 volts) . General-purpose analog voltmeters may have an accuracy of a few percent of full scale and are used with voltages from a fraction of a volt to several thousand volts. Digital meters can be made with high accuracy, typically better than 1% .