There are many different types of headaches, but they can be broadly classified as primary and secondary headaches. The Diagnosis of Headaches involves understanding the epidemiology of headaches, identifying the signs of secondary headaches, and applying the diagnostic criteria outlined in the International Classification of Headache Disorders. Clinicians should have a clear understanding of SNNOOP10 to indicate secondary headache. Furthermore, the evaluation of patients who present with a thunderclap headache should be conducted with great care and detail.