The third-most abundant element in the universe by mass, Oxygen is a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. Perhaps the most vital gas for humans in the whole wide world, Oxygen is important not just in respiration but for other processes like combustion as well.
In addition to its respiratory uses, humans have discovered its benefits as a mild euphoric and is becoming popular for recreational use in oxygen bars, sports and pyrotechnic applications. However, the benefits of Oxygen are not just limited to human consumption. It is a vital element of numerous industrial processes including smelting, oxy-cracking, catalytic oxidation and much more.
Furthermore, oxygen is also used in medical applications, metal cutting and welding, as an oxidizer in rocket fuel, and in water treatment. Burning Acetylene with Oxygen in oxyacetylene welding produces a very hot flame that can be used to cut metal up to 24″ thick.