A ventilator is a medical device that helps patients breathe when they are unable to do so on their own. It delivers a mixture of air and oxygen to the lungs through a tube inserted into the patient's airway. Ventilators are commonly used in hospitals for patients with severe respiratory conditions, such as pneumonia or COVID-19. These machines can be adjusted to control the amount of air and oxygen delivered, as well as the breathing rate. By providing mechanical support, ventilators help maintain adequate oxygen levels in the blood and remove carbon dioxide, which is crucial for patient recovery.