The main gas in the Earth’s atmosphere is nitrogen, which makes up about 78% of the atmosphere by volume. Oxygen follows, constituting around 21%. The remaining 1% consists of trace gases, including argon, carbon dioxide, and other gases. Nitrogen is essential for life as it is a fundamental building block of amino acids and proteins. The presence of these gases is critical for processes such as respiration in animals and photosynthesis in plants. The atmosphere also plays a vital role in regulating the Earth's climate and protecting it from harmful solar and cosmic radiation.