Technological progress in neurosurgery - preoperative investigation of the exact anatomy of the patient, detailed planning of the procedure, and use of endoscopes and videosurgery -- have made approaches for intracranial microsurgical procedures smaller compared to historically standard neurosurgical approaches. Building on the previous works "Endoscopic Anatomy for Neurosurgery" and "Keyhole Concept in Neurosurgery," this book offers a systematic overview of keyhole approaches in the daily work of a neurosurgeon. The approaches, strategies, indications and technical details described here are complemented by anatomical pictures, schemes, and artists' illustrations, and analyzed with regard to geometric boundaries and the topography of the target structures.