Millivolt Ampere Reactive (mVAR) is the metric‑scale unit of reactive power, representing one‑thousandth of a volt‑ampere reactive (VAR) and symbolized by “mVAR.” It quantifies the portion of alternating‑current (AC) power that oscillates between source and load without performing useful work, reflecting the energy stored and released by inductive or capacitive elements in a circuit. Engineers and technicians use mVAR to size capacitors, design power factor correction systems, and monitor the efficiency of industrial motor drives, renewable‑energy inverters, and smart‑grid installations. By tracking millivolt‑ampere reactive values, professionals can minimize losses, avoid over‑loading transformers, and ensure compliance with utility standards, making mVAR a critical metric for both practical electrical maintenance and advanced scientific analysis of AC power quality.