What is digital multi-meter?

A digital multimeter (DMM) is a test tool used to measure two or more electrical values—principally voltage (volts), current (amps) and resistance (ohms). It is a standard diagnostic tool for technicians in the electrical/electronic industries. DMMs are used to troubleshoot electrical problems on a wide array of devices such as electronic equipment, motor controls, domestic appliances, power supplies, and wiring systems.