Headache is the symptom of pain anywhere in the region of the head or neck. It occurs in migraines (sharp, or throbbing pains), tension-type headaches, and cluster headaches. Frequent headaches can affect relationships and employment.There is also an increased risk of depression in those with severe headaches.Headaches can occur as a result of many conditions whether serious or not. There are a number of different classification systems for headaches. The most well-recognized is that of the International Headache Society. Causes of headaches may include dehydration, fatigue, sleep deprivation, stress, the effects of medications, the effects of recreational drugs, viral infections, loud noises, common colds, head injury, rapid ingestion of a very cold food or beverage, and dental or sinus issues.Treatment of a headache depends on the underlying cause, but commonly involves pain medication. A headache is one of the most commonly experienced of all physical discomforts.About half of adults have a headache in a given year.Tension headaches are the most common, affecting about 1.6 billion people (21.8% of the population) followed by migraine headaches which affect about 848 million (11.7%).