A stroke occurs when the blood supply to the brain is interrupted or reduced, depriving brain tissue of oxygen and nutrients. There are two main types of stroke: ischemic, caused by a blockage in an artery, and hemorrhagic, caused by a ruptured blood vessel in the brain. Symptoms vary depending on the affected area of the brain and can include paralysis, confusion, vision changes, and headaches. Treatment depends on the type of stroke, but may involve clot-busting drugs, surgery, or lifestyle changes to prevent future strokes such as controlling risk factors like high blood pressure, smoking, diabetes, and obesity. Prognosis depends on the severity and location of damage to the brain.