A multi meter or a multi tester, also known as a vom (volt-ohm meter or volt-ohm-millimeter ), is an electronic measuring instrument that combines several measurement functions in one unit. A typical multi meter can measure voltage, current, and resistance. Analog multi meters use a micro ammeter with a moving pointer to display readings. Digital multi meters(dmm, dvom) have a numeric display, and may also show a graphical bar representing the measured value. Digital multi meters are now far more common but analog multi meters are still preferable in some cases, for example when monitoring a rapidly varying value.
A multi meter can be a hand-held device useful for basic fault finding and field service work, or a bench instrument which can measure to a very high degree of accuracy. They can be used to troubleshoot electrical problems in a wide array of industrial and household devices such as electronic equipment, motor controls, domestic appliances, power supplies, and wiring systems.