Electrosurgical generator units (ESUs) facilitate therapeutic endoscopy by supplying the high-frequency electrical current required to use many endoscopic accessories. The term electrosurgical energy describes the transformation of alternating electrical current produced by the ESU into thermal energy within tissue.

Electrosurgical generators complete electrical circuits by using either monopolar or bipolar devices. The difference between the 2 relates to the location of the active and the neutral electrodes.