The Earth's atmosphere is composed mainly of nitrogen and oxygen, which together make up about 99% of the atmospheric composition. Nitrogen constitutes about 78% of the atmosphere, while oxygen accounts for around 21%. Other gases, such as argon, carbon dioxide, and trace gases, make up the remaining fraction. This composition is crucial for human life, as oxygen is essential for respiration, while nitrogen plays a significant role in the ecosystem and atmosphere's stability. Other components contribute to weather patterns and climate as well.