Nitrogen ( /ˈnaɪtrɵdʒən/ NY-trə-jən) is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.09% by volume of Earth's atmosphere. The element nitrogen was discovered as a separable component of air, by Scottish physician Daniel Rutherford, in 1772.

Nitrogen is a common element in the universe, estimated at about seventh in total abundance in our galaxy and the solar system. Its occurrence there is thought to be entirely due to synthesis by fusion from carbon and hydrogen in supernovas. Due to the volatility of elemental nitrogen and its common compounds with hydrogen and oxygen, nitrogen is far less common on the rocky planets of the inner solar system, and it is a relatively rare element on Earth as a whole. However, as is the case on Earth, nitrogen and its compounds occur commonly as gases in the atmospheres of planets and moons that have atmospheres.