The most abundant gas in Earth's atmosphere is nitrogen, which makes up approximately 78% of the atmosphere by volume. This colorless, odorless gas plays a crucial role in the Earth's ecosystem, serving as a vital component of various biological processes, including the nitrogen cycle. Despite its abundance, nitrogen is relatively inert and does not readily react with other elements. This property helps stabilize the atmosphere and is essential for maintaining a balanced environment. Oxygen follows nitrogen as the second most abundant gas, comprising about 21% of the atmosphere.