Headache is defined as a pain arising from the head or upper neck of the body. The pain originates from the tissues and structures that surround the skull or the brain because the brain itself has no nerves that give rise to the sensation of pain (pain fibers). Several types of headaches exist, with tension headaches being the most common. Cluster headaches are painful and happen in groups or “clusters,” while migraines are a moderate-to-severe type of headache.