The primary component of Earth's atmosphere is nitrogen, which makes up about 78% of the atmosphere by volume. It is a colorless, odorless gas that is essential for life as it forms the basis for amino acids and proteins in living organisms. While nitrogen is relatively inert and does not readily react with other elements, it plays a critical role in the nitrogen cycle, which includes conversion and reuse in ecosystems. Oxygen, at around 21%, is the second most abundant gas, necessary for respiration in many life forms. Together, these gases support life and influence weather patterns on Earth.