A Clamp Meter combines a current clamp with the basic functions of a digital multimeter, also called DMM. Clamp the "jaw" around a conductor to measure current. Over the years current clamp meters have evolved to include a host of additional features.

Take a look at this Amprobe clamp meter video. It displays Power and measures Total Harmonic Distortion (THD). Amprobe, now part of Fluke, invented the first clamp meter in 1948 and is still a leader today.