subarachnoid hemorrhage is a medical condition where there is bleeding in the space between the brain and the tissues that cover it. This area, known as the subarachnoid space, is filled with cerebrospinal fluid, which helps protect the brain. When bleeding occurs, it can lead to increased pressure on the brain and can cause serious complications. The most common cause of subarachnoid hemorrhage is the rupture of an aneurysm, a weak spot in a blood vessel. Symptoms often include a sudden, severe headache, neck stiffness, and nausea. Prompt medical attention is crucial, as this condition can be life-threatening if not treated quickly.