An oxygen mask is a device designed to deliver oxygen to individuals who may have difficulty breathing. It is commonly used in medical settings, such as hospitals, and in emergency situations, like aircraft emergencies. The mask fits over the nose and mouth, allowing the user to inhale oxygen from a connected source. In aviation, oxygen masks are crucial for passengers and crew when flying at high altitudes, where the air pressure is lower and oxygen levels are reduced. These masks ensure that individuals receive adequate oxygen, helping to prevent hypoxia, a condition caused by insufficient oxygen in the body.