Interferential therapy (IFT) is introduced by Dr. Nemec  in the early 1950’s.He wanted to overcome the problems of discomfort caused by low-frequency currents, while maintaining their claimed therapeutic effect. It remained disappear until 1970s, when work on pain mechanism by Melzack/Wall showed that pain could be reduced by stimulating primary afferent neurons. The transcutaneous application of alternating medium-frequency electrical currents are applied to the body in such a manner to produce  amplitude modulated low frequency current within in the body for therapeutic purposes. It is the production of low frequency current in the body tissue by the simultaneous application of two different medium frequency currents. As the low frequency current is the result of interference of two different medium frequency currents, it is named as – interferential current.