This document provides information on interferential therapy (IFT), including its history, principles, applications, and treatment protocols. It discusses how IFT works by producing an interference current within the body using two medium frequency currents of slightly differing frequencies. IFT is used to reduce pain and muscle spasm, promote tissue healing, and reduce edema. Common treatment parameters and applications are outlined, along with contraindications and potential dangers of IFT. The document also describes the proper procedure for administering IFT treatments.