An endotracheal tube is a medical device used to maintain an open airway in patients who are unable to breathe on their own. It is a flexible tube that is inserted through the mouth or nose and into the trachea, allowing for direct access to the lungs. This procedure is often performed during surgeries or in emergency situations to ensure proper ventilation. The tube is typically connected to a ventilator, which helps deliver oxygen and remove carbon dioxide from the body. Proper placement of the endotracheal tube is crucial, as incorrect positioning can lead to complications such as inadequate oxygenation or injury to the airway.