Stridor is an abnormal high-pitched respiratory sound caused by partial airway obstruction. It can be inspiratory, expiratory, or biphasic depending on the location and nature of the obstruction. A thorough history and physical exam seeking signs of airway distress are important to determine the underlying cause and severity. Potential causes include infections, tumors, vascular anomalies, and traumatic or congenital structural abnormalities. Treatment involves addressing the specific cause through medications, surgery, or assisting ventilation depending on the severity and location of airway compromise.