Nitrogen (N2) is a colorless, odorless, and tasteless gas that makes up 78.09% (by volume) of the air we breathe. It is non-flammable and it will not support combustion. Nitrogen gas is slightly lighter than air and slightly soluble in water. It is commonly thought of and used as an inert gas, but it is not truly inert. Nitrogen gas is also used to provide an unreactive atmosphere. It is used in this way to preserve foods, and in the electronics industry during the production of transistors and diodes. Large quantities of nitrogen are used in annealing stainless steel and other steel mill products.