Dirty electricity is a form of electromagnetic pollution or radiation. It is also called electromagnetic interference (EMI) or electrical "noise". It refers to powerful, high-frequency electrical energy traveling along the wiring in buildings where only standard 60-Hertz AC electricity should be. It is also frequently referred to as harmonic distortion as it interferes with and distorts the fundamental 60 Hertz sinusoidal waveform. This distortion also results in unusable energy which is usually called reactive energy.