The gas primarily responsible for the Earth's atmosphere is nitrogen, comprising about 78% of the atmosphere. Oxygen is the second most abundant gas, making up approximately 21%. Other gases, such as argon, carbon dioxide, and trace gases, are also present. Nitrogen plays a crucial role in various biological processes and helps in maintaining the planet's climate. The atmosphere protects life by filtering harmful solar radiation and regulating temperature. Its composition is vital for sustaining ecosystems and is influenced by various natural and anthropogenic factors.