These lectures provide the basic understanding of various clinical signs and symptoms from a thorough insight into basic principles of neurology, (neuro-)physiology and neuroanatomy. The primary audience is therefore students whose future work will be in these fields, however with the goals of typical clinical medical specialists driving the technological evolution. These students are primarily trained to contribute to new developments and innovations in neurology and clinical neurophysiology. They are confronted with patients but are not trained for routine patient care. Rather, their skills are technologically based knowledge, ranging from sensor technology to mathematical modeling, or advanced signal analysis. Essentials of neurophysiology therefore presents a hybrid of information, both from the clinical field and from basic physiology, with a very strong emphasis on concepts, including mathematical descriptions if felt necessary for a thorough understanding, but with less emphasis on various diseases. However, prototype examples of neurological diseases are discussed.In this respect, more technically and/or research minded medical students, residents, neurologists and clinical neurophysiologists, will also find this text useful. The topics covered range from basic neuroanatomy to physiology, from membrane potentials to interneuronal communication. In addition, the author explains how various measurements on the human nervous system can be performed, including a treatise on medical measurements in general. A short chapter on medical decision making is included, since this is a potential field for innovation, as well (computer supported decision making). Throughout the text, we will present various examples of neurological diseases.