Here are the 8 most common gases in Earth's atmosphere, in order of abundance:

1. Nitrogen (N2): 78.08%

2. Oxygen (O2): 20.95%

3. Argon (Ar): 0.93%

4. Carbon Dioxide (CO2): 0.04%

5. Neon (Ne): 0.0018%

6. Helium (He): 0.00052%

7. Methane (CH4): 0.00017%

8. Krypton (Kr): 0.00011%

Note: The percentages are approximate and can vary slightly depending on factors like location and altitude.