Chronic daily headache (CDH) is the most common presenting headache in headache specialty practices and can be devastating in its effect on patients, their families, and physicians who care for them. The International Classification of Headache Disorders (ICHD-2) is the standard for codification of headache. Medication overuse headache (MOH) is currently the most common cause of CDH in the industrialized countries. CDH presents as any head pain that occurs frequently. MOH has a typical presentation that can be recognized along with other primary headache types. MOH remains the single most common factor in the transformation of episodic headache to chronic headache, and is the default diagnosis when patients present with CDH. Long-term strategies to revert chronic headache to an episodic occurrence include biobehavioral, lifestyle, and integrative approaches in addition to medication and education. CDH is a contributor to suffering and economic burden worldwide.