Headache is a challenging symptom for both patients and providers. Nearly 45 million people suffer from chronic headaches, and headache is a common cause for primary care visits. The primary headache syndromes are those headaches that are considered idiopathic, including migraine, tension type headache (TTH), and cluster headache. Secondary headache syndromes usually can be found to have a treatable cause, which will result in “cure” of the headache. This chapter discusses diagnostic classifications of headaches, using the updated and revised version of the International Headache Society (IHS) criteria. Headache, with its major symptom being pain, is subject to cultural differences in patient experience, meaning, and outcomes. Cluster headache should be recognized by the primary care provider because the syndrome is often easily diagnosed and is highly treatable. The headache may overlie the site of the hematoma as it forms or be more generalized and bandlike.