A person is said to have suffered a stroke or a “Passover” when symptoms indicate that the cells in a particular area of the brain have suddenly ceased to function. The individual may lose the use of only a part of the body (e.g. an arm or leg or both).
Strokes occur either when a blood vessel becomes clogged thus hampering blood flow to the brain (ischemic stroke) or when a blood vessel ruptures causing blood to leak into the brain (haemorrhagic stroke).
See more information here: What is a Stroke