Decompressive craniectomy is a surgical technique used to relieve increased intracranial pressure by removing a portion of the skull bone and opening the dura mater. It allows swollen brain tissue room to expand and reduces pressure. The document discusses the history of the procedure, indications such as severe traumatic brain injury and malignant stroke, types including decompressive hemicraniectomy and bifrontal craniectomy, potential complications like subdural fluid collections, and the role of later cranioplasty. While controversies remain, decompressive craniectomy can be life-saving for carefully selected patients with medically refractory elevated intracranial pressure.