A stroke occurs when a blood vessel that carries oxygen and nutrients to the brain is either blocked by a clot or bursts. When this happens, part of the brain can't get blood or the oxygen it needs, so it begins to die. This kills brain cells in the area of the brain where the blockage/burst occurred.
Brain cells can't regenerate like other cells in our bodies. Once a brain cell is dead, it can't be repaired. So, early recognition is key.