The Earth's atmosphere is primarily composed of nitrogen and oxygen, which together make up about 99% of its composition. Nitrogen constitutes approximately 78% of the atmosphere, while oxygen accounts for around 21%. Other gases present in trace amounts include argon, carbon dioxide, neon, and methane. The atmosphere plays a critical role in sustaining life by providing the necessary gases for respiration, protecting the planet from harmful solar radiation, and regulating temperatures through the greenhouse effect. Understanding the composition and behavior of Earth's atmosphere is essential for studying climate change and environmental science, as these gases contribute to global climate patterns and weather systems.