Oxygen tanks are essential medical devices used to provide oxygen to patients in need, but they can also be referred to by various other names. One common term for an oxygen tank is an oxygen cylinder, which is usually made of steel or aluminum and comes in different sizes. Another name for an oxygen tank is an oxygen container, which is used to hold and store compressed gas. Oxygen bottles and oxygen canisters are also used as alternative names for oxygen tanks. Some hospitals and medical facilities refer to them as oxygen reservoirs. Whatever name they go by, oxygen tanks fulfill a vital function in delivering life-sustaining oxygen to patients who require supplemental oxygen therapy.