The thin layer of gas that sorrounds in earth is called atmosphere.
Earth's atmosphere is separated into five layers know as;
The Troposphere,
Stratosphere,
Mesosphere,
ionosphere, and
exosphere.
And earth's atmosphere is a thin layer of gases that surrounds the earth.
And it's composed of 78% nitrogen, 21% oxygen, 0.9% argon, 0.03 carbon dioxide, and other trace amount of gases.