Migraine is a painful neurological condition, of which the most common symptom is an intense and disabling episodic headache. Migraine headaches are usually characterised by severe pain on one or both sides of the head. Absent serious head injuries, stroke, and tumours, the recurring severity of the pain indicates a vascular headache rather than a tension headache. Migraines are often accompanied by photophobia (hypersensitivity to light), phonophobia (hypersensitivity to sound) and nausea. Available evidence suggests that migraine pain is one symptom of several to many disorders of the serotonergic control system, a dual hormone-neurotransmitter with numerous types of receptors. Two disorders, classic migraine with aura (MA, STG) or common migraine without aura (MO, STG), are currently proved to be genetic. Additional migraine types are suspected and could be proved to be genetic. Migraine understood as several or many disorders could explain the inconsistencies, especially if a single patient has more than one genetic type. This book presents important new research from around the globe.