Fibromyalgia (FM) is a complex neurological disorder characterized by central sensitization, dysfunction in pain processing, and aberration in the descending inhibitory pathways. Alteration in muscle metabolism and mitochondrial dysfunction also may contribute to the pathophysiology of this syndrome. The clinical presentation of FM is diverse. Patients usually present with persistent localized or diffuse pain in addition to various non-painful comorbidities. The diagnosis of FM is based on the patient’s history and physical examination. Serologic biomarkers are used to exclude other disease entities. More research is needed to understand the complexity of this syndrome and its systemic manifestations.