Migraine is a common, disabling disorder of the central nervous system. The disorder has three key features. The tendency is largely inherited, the sufferer is sensitive to exogenous and endogenous triggers that very often involve challenges to normal homeostatic biology, and the attack phenotype, when severe, is the stereotypical migraine attack. The attack itself consists of an abnormal perception of otherwise normal circumstances, such as pain without evidence of primary nociceptive activation, and light and sound sensitivity without change in ambient stimuli. The disturbance in the brain is of the subcortical aminergic sensory modulatory systems, and probably includes brainstem, hypothalamic, and thalamic changes that produce the rich clinical presentation seen in practice.