The ozone layer is a layer rich in ozone gas present in the earth's atmosphere. It lies between 10-40 km in the stratosphere layer of atmosphere. The atmosphere is very thin at polar regions as compared to equatorial regions. Thus the thickness of ozone layer is not uniform everywhere and varies from region to region. This layer absorbs most of the harmful UV radiation from the sun, thus protecting people on the earth. These UV radiations can cause skin cancer, genetic mutations and other harmful ailments. They also have harmful effect on vegetation. So the ozone layer acts as a protective cover for the earth.