This document discusses stridor, which is a noisy respiration caused by turbulent airflow through a narrowed airway. It defines three types of stridor based on where in the respiratory cycle the noise occurs: inspiratory, expiratory, and biphasic. Common causes of stridor in children include infections like croup as well as foreign objects. Diagnosis involves examining the timing, quality and other characteristics of the noise along with imaging tests to find the specific obstruction. Treatment depends on the underlying cause but may include medications to reduce swelling like steroids or racemic adrenaline to ease breathing.