A headache is when your head hurts. It is not when you hit your head with something and made it hurt that way, but when your head hurts from inside. Headache is the symptom of pain in the face, head, or neck.

A headache can be caused by one of several things, which are listed here:

• Fever
• Watching television or looking at a computer screen for a long time.
• Being tired or sleepy.
• As an effect of stress.
• By other neurological conditions ('neurological' means touching the nerves and the brain), like with epilepsy

The second edition of the International Headache Classification (ICHD-2) defines more than 220 different types of headaches in three categories:

• Primary headaches, for example migraine, tension headache and cluster headache.
• Secondary headaches
• Cranial neuralgias, central and primary facial pain and other headaches

Many headaches can be relieved with analgesics like aspirin.