An oxygen mask is a piece of equipment used to deliver oxygen to a person who is having difficulty breathing. It is commonly used in medical settings, such as hospitals and ambulances, but can also be used in emergency situations, such as during a fire or in high-altitude environments.

There are several types of oxygen masks, including simple face masks, nebulizing masks, non-rebreather masks, high & medium concentration masks, and venturi masks, etc. Each type is designed to deliver oxygen at a specific flow rate and concentration, depending on the needs of the patient.

Oxygen masks are typically used when a person's oxygen levels are too low, either due to a medical condition or a lack of oxygen in their environment. By delivering oxygen directly to the person's lungs, an oxygen mask can help improve their breathing and increase their oxygen levels.