A headache is a pain in your head or face that's often described as a pressure that's throbbing, constant, sharp or dull. Headaches can differ greatly in regard to pain type, severity, location and frequency. Headaches are a very common condition that most people will experience many times during their lives. They're the most common form of pain and are a major reason cited for days missed at work or school, as well as visits to healthcare providers. While most headaches aren't dangerous, certain types can be a sign of a more serious condition.