A multimeter is an electronic measuring device that can measure various electrical quantities such as voltage, current and resistance. It usually consists of a display showing the measured values and several inputs through which the electrical contacts can be connected to the device.

A voltage tester is a simpler measuring device specifically designed to check voltage in a circuit. It usually consists of an indicator lamp and two test probes. When the voltage tester is inserted into a voltage source, the indicator lamp illuminates to indicate that voltage is present.

Both of these devices are useful for electricians, electronics technicians, and do-it-yourselfers to diagnose electrical problems, check circuits, or test electrical components. It is important to observe proper use of the equipment according to the manufacturer's instructions and to take safety precautions to avoid injury or damage.