Intraoperative electrophysiological recordings are gradually becoming part of standard medical practice, mainly because they offer an objective and effective way to assess the functional integrity of the nervous system of a patient during the course of an orthopedic, neurological, or vascular surgery. Continuous monitoring of spontaneous and triggered bioelectrical activity not only can avert damage of neurological structures that are at risk during certain surgical maneuvers, but also allows identification of specific neuronal structures and landmarks that cannot be easily recognized on anatomical grounds only. This series on neurophysiological monitoring will introduce various techniques of monitoring available today, the rationale for their intraoperative use, and the main principles on which they are based. Recommendations for proper implementation and troubleshooting will also be given. The present article gives a general overview of the procedures.