Headaches are sometimes a symptom of a disease or disorder such as influenza or sub arachnoid hemorrhage (SAH). Most headaches, however, occur independently of other disorders, develop gradually, clear up in few hours and leave no after effects.
Majority of headaches, however painful, are likely to be only temporary, brought out by strain or muscular tissues, or by changes in blood vessels in head, neck or both.
Other factors, either alone or combined that give headaches include stress, too little or too much sleep, overeating or drinking, and a noisy and stuffy environment. Job stress, over thinking, strain over eyes due to continuous work on computer etc also result in stress.

Tension headache: Occurs due to strain on facial, neck and scalp muscles. Stress may also result in contraction of muscles head and neck cause pain.

Vascular headache: Occurs due to swelling of blood vessels in head area that result in stretching of their walls. It can result in tightening of head and neck muscles and cause in addition, a tension type of pain producing mixed type of headache.

Migraine: Characterized by periodic headaches usually on one side, generally with other symptoms such as nausea, vomiting, and disturbed vision, that almost completely incapacitates you for as long as they last. Migraine with headache tends to run in families. Certain foods including cheese, chocolates, caffeine, red wine, provoke attacks. Often there is relationship between recurrent headaches and menstruation or stress.

Cluster headaches: A variant of migraine, most commonly seen in men, characterized by sporadic episodes of extreme pain on one side of head, typically begin in night with an intense throbbing pain. Often lasts for several hours and then disappears, only to return within few hours or at same time next day. After several days of repeated episodes, headaches disappear and they may not recur for several years.