Thorough understanding of electricity, electronics, biophysics, neurophysiology, and neuroanatomy renders more tractable otherwise complex electrophysiologically-based targeting. The textbook integrates these subjects in a single resource. Ultimately, electrophysiological monitoring required controlling the movement of electrons in electronic circuits. Thus, the textbook begins with fundamental discussions of electrons, the forces moving electrons, and the electrical circuits controlling these forces. The forces that allow recording and analysis also permeate the environment producing interference, such as noise and artifact. The textbook discusses noise and artifact and the measures to avoid or suppress them. The textbook discusses interpretive principles and methods for translating electrophysiological information collected along a trajectory into an understanding of the trajectory's functional-anatomical location, as well as its optimal location and direction. Forms included allow one to document observations, consult algorithms, and interpret data. Other discussions cover safe brain stimulation, correct interpretation of patient responses, procedures of targeted neurological examinations to assess patients' condition in response to stimulation and any surgical consequences, various aspects and limitations of image-based surgical planning, and principles governing use of electrode-guiding mechanical devices.