This document provides an overview of basic electrical concepts to help readers better understand energy efficiency. It defines key terms like energy, British Thermal Units, the WAGES acronym to remember the main energy sources (water, air, gas, electric, steam), electrical resistance, power distribution in single and three-phase systems, real and reactive power, power factor and how it is calculated, causes of low power factor including displacement and total power factor, load factor calculation, and the power triangle relationship between voltage, current, real power, reactive power and apparent power.