In spite of the fact that stroke is a significant public health problem, it is still poorly recognized that it consists of a number of heterogeneous subtypes. The major subtypes are ischemic stroke (about 80%), intracerebral hemorrhage (about 10%), and subarachnoid hemorrhage (about 5%). All have different mechanisms and risk factor profiles. Ischemic stroke subtypes may be classified mechanistically, topographically, or clinically. Mechanistic subgroups include: artery-to-artery embolism, lacunar infarction, cardioembolic mechanisms, aortic arch atheroma, borderzone and hemodynamic mechanisms, and other, rarer, causes. While some commonality of risk factor and mechanistic profiles does exist between stroke subtypes, there are significant differences that have implications for stroke prevention and management...