What specifically causes headache?

Headaches can be caused by various factors, including tension in the muscles, stress, dehydration, hormonal changes, and underlying medical conditions. They can also result from environmental factors like loud noises, bright lights, or strong smells. Additionally, headaches may be triggered by certain foods, lack of sleep, or excessive screen time. Each type of headache, such as tension, migraine, or cluster headaches, may have specific triggers and underlying mechanisms.