A multimeter or a multitester, also known as a VOM (volt-ohm-milliammeter), is an electronic measuring instrument that combines several measurement functions in one unit.
A typical multimeter can measure voltage, current, and resistance.
Analog multimeters use a microammeter with a moving pointer to display readings. Digital multimeters (DMM, DVOM) have a numeric display, and may also show a graphical bar representing the measured value. Digital multimeters have rendered analog multimeters obsolescent because they are now lower cost, higher precision, and more physically robust.
A multimeter 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.
Basic testers measure voltage, amperage, and resistance and can be used to test the continuity of a circuit. More advanced multimeters may test alternating/direct current voltage and amperage, resistance, capacity, conductance, decibels, duty cycle, frequency, Inductance, Temperature Celsius or Fahrenheit. Accessories or special sensors can be attached to some multimeters for additional readings, such as: light level, acidity, alkalinity, wind speed, relative humidity.
Multimeters are available in a wide range of features and prices. Cheap multimeters can cost less than US$10, while laboratory-grade models with certified calibration can cost more than US$5,000.