The parts of the atmosphere as follows:
Troposphere which extends up to 11 km above the surface of the earth. This is the lowest layer and the one we are usually observing.
Stratosphere which extends up to 50 km above the surface of the earth. This region is where jet planes fly and where ozone absorbs UV radiation.
Mesosphere which extends up to 87 km above the surface of the earth. The coldest parts of the atmosphere exist here.
Thermosphere which extends up to 500 km above the earth's surface. This region can become very hot due to the sun's activity.
The region beyond all of these, where space starts is the exosphere
