Headache is a pain in any region of the head. Headaches may occur on one side known as migraine or on both sides of the head, be isolated to a certain location, radiate across the head from one point, or have a viselike quality. A headache may appear as a sharp pain, a throbbing sensation, or a dull ache. Migraine is a headache of varying intensity, often accompanied by nausea and sensitivity to light and sound.