The main gas that makes up our atmosphere is nitrogen, which constitutes about 78% of the atmosphere by volume. It is a colorless, odorless gas that plays an essential role in maintaining the balance of gases in the atmosphere. Aside from nitrogen, other significant components include oxygen (about 21%) and trace amounts of other gases such as carbon dioxide, argon, and water vapor. Nitrogen is crucial for living organisms as it is a fundamental component of amino acids and proteins, which are vital for biological processes and the structure of nucleic acids.