The dominant gas in Earth’s atmosphere is nitrogen, which constitutes approximately 78% of the atmosphere by volume. Nitrogen is an inert gas, meaning it does not readily react with other chemicals under standard conditions. This property allows it to play a crucial role in maintaining the stability of the atmosphere. While nitrogen is not directly usable by most living organisms, it is vital for life, as it is a key component of amino acids and nucleotides, which are essential for proteins and DNA. In addition to nitrogen, the atmosphere also contains oxygen (about 21%) and trace amounts of other gases.