The term TENS itself may represent any of the various methods of electrical stimulation using electrodes directly on the surface of the skin. Other than pain relief, TENS is also commonly used to help stimulate muscle contractions.Pain relief is accomplished by exciting sensory nerves and thereby stimulating either the pain gate mechanism and/or the opioid system. The different methods of applying TENS relate to these different physiological mechanisms. There is also no “correct” setting to achieve ideal results, in clinical practice results will vary depending on the person and patients should be encouraged to provide feedback about which settings and ranges provide the best results for them.TENS is commonly used as a treatment technique because it is a simple, non-invasive and easy to apply method that has much fewer side effects compared with drug therapy. A few percentage of patients have complaints of an allergic type skin reaction which can be due to the electrodes themselves, the type of gel used, or the tape that can be used to hold the electrodes in place on the skin.Research provides evidence that when used properly TENS provides significantly greater pain relief than a placebo intervention. There is an extensive research base for the therapeutic use of TENS in a clinical setting and the intervention is widely popular for its ease of use and effectiveness.