* Nitrogen (N2): Makes up about 78% of the atmosphere.

* Oxygen (O2): Makes up about 21% of the atmosphere.

* Argon (Ar): Makes up about 0.93% of the atmosphere.

These are the three most abundant gases, making up over 99% of the atmosphere.

Other Gases in Small Amounts:

* Carbon dioxide (CO2): Although a small percentage, it's a crucial greenhouse gas.

* Neon (Ne), Helium (He), Krypton (Kr), Xenon (Xe): These noble gases are present in trace amounts.

* Water vapor (H2O): The amount varies greatly depending on location and weather conditions.

* Ozone (O3): Important in the stratosphere but also a pollutant in the lower atmosphere.

Important Note:

* "Pure air" is a concept, as air is never truly pure in nature. It always contains varying amounts of pollutants, dust, and other substances.

* The composition of air can fluctuate depending on altitude, location, and time of day.