Oxygen is a vital element and has various purposes, the most important of which is for breathing. Animals and humans require oxygen in the air and water to breathe and live. Most forms of combustion also require oxygen to burn. The more oxygen, the hotter and larger the fire: a reason why some fire extinguishers work by reducing and preventing oxygen in burning materials.
Oxygen is a part of hundreds of thousands of organic compound. While it is a naturally occurring element, it can be produced and prepared in a laboratory through electrolysis, fractional distillation and liquefaction and is mostly used in commercial purposes like in the steel industry. Oxygen is capable of combining with most other elements and can generate enormous temperatures, making it an ideal element for smelting iron from ore, as an oxidizer for spacecraft fuel and water treatment. Gaseous oxygen is also used to generate energy in ships and generators.
Hospitals always keep a stock of oxygen tanks for patients who can't breathe or have difficulty breathing, such as victims of carbon monoxide poisoning. Scuba divers, mountaineers, and astronauts also use the same artificial breathing apparatus. Ozone, the atmospheric layer that is made of three oxygen atoms, creates a protective barrier and shields the Earth's surface from the sun's harmful ultraviolet rays.