This document discusses syncope, which is a transient loss of consciousness due to temporary reduced blood flow to the brain. It notes that syncope accounts for around 1% of emergency department visits and is a common cause of hospitalization for those over 65. Establishing the exact cause is difficult as the patient has usually recovered by the time they are examined. The document then discusses various causes of syncope and nonsyncopal attacks that can be mistaken for syncope. It provides breakdowns of common causes by age group and discusses the natural history and risk stratification of syncope of unknown cause in the emergency department.