A headache is a common condition characterized by pain or discomfort in the head, scalp, or neck, varying in intensity, duration, and underlying cause. Primary headaches include tension-type headaches, which often cause a dull, pressing pain; migraines, which may involve throbbing pain, nausea, and sensitivity to light or sound; and cluster headaches, which produce severe, one-sided pain around the eye. Secondary headaches result from underlying conditions such as infections, dehydration, sinus problems, head injury, or high blood pressure. Symptoms may include pressure, pulsating pain, tightness, or accompanying neurological signs depending on the type. While most headaches are temporary and benign, sudden, severe, or persistent headaches—especially with additional symptoms like confusion, weakness, or fever—require medical evaluation.