The Earth's atmosphere is primarily composed of nitrogen (N2), making up about 78% of the atmosphere.

Here's a breakdown of the main gases in the atmosphere:

* Nitrogen (N2): 78%

* Oxygen (O2): 21%

* Argon (Ar): 0.93%

* Carbon dioxide (CO2): 0.04%

* Other gases: Trace amounts of neon, helium, methane, krypton, hydrogen, and xenon.

While nitrogen is the most abundant, oxygen is the gas we breathe and is essential for life on Earth. Carbon dioxide, though a small percentage, plays a crucial role in regulating Earth's temperature through the greenhouse effect.