Book excerpt: This book describes the developments and improvements in electroencephalography (EEG). In recent years, digital technology has replaced analog equipments, and it is now possible to easily record and store EEG tracings and to quickly recall previously acquired material for subsequent analysis. In addition, not only static figures, but also electronic supplementary materials can be included in books, enabling EEGs to be viewed in real-time. In clinical practice, EEG still represents the most important functional examination in the study CNS development and its anatomical and physiological integrity throughout life. In the pathological context, EEG provides indispensable diagnostic information for classification of epileptic syndromes, and it is also valuable in all the other CNS diseases (infectious, cerebrovascular, neurodegenerative, etc). Furthermore, monitoring EEG can be widely used in emergency settings, such as emergency departments or intensive care units. In comatose patients, EEG provides information regarding prognosis and evaluation of the sedative effect of anesthetic drugs. Written by a group of leading national and international experts, it offers a substantial, yet practical, EEG compendium, which serves as a reference resource for physicians and neurodiagnostic technologists as well as physicians-in-training, researchers, practicing electroencephalographers and students.