A stroke occurs when blood flow to the brain is disrupted, depriving brain cells of oxygen. There are two main types of stroke - one caused by a blockage cutting off blood flow, and one caused by bleeding within the brain. Symptoms depend on the affected brain region and may include loss of movement, speech, or vision. Risk factors include age, sex, race, diabetes, high blood pressure, prior strokes or mini-strokes, heart conditions, and lifestyle factors like smoking, diet, weight, and alcohol use. Making healthy choices can help reduce risks within one's control.