ozone layer is a layer of the Earth's atmosphere in which the concentration of ozone gas is relatively high. Life on earth is possible due to the ozone layer. This layer absorbs 93–99% of the sun's high-frequency ultraviolet light, which is harmful to life on Earth. More than 91% of the ozone of the Earth's atmosphere is present here.
It is located mainly in the lower part of the stratosphere from about 10 km to 50 km above the Earth's surface, although its thickness varies seasonally and geographically.
The ozone layer was discovered in 1913 by French physicists Fabri Charles and Henri Busson. Even before this, when scientists looked at the spectrum of light coming from the Sun, they found that there were some dark areas in it and no radiation of wavelength less than 310 nm was coming from the Sun to Earth.  Scientists concluded from this that some element is absorbing the necessary ultraviolet rays, creating a black area in the spectrum and no radiation is visible in the ultraviolet portion.
The part of the spectrum of light that was not visible from the Sun was completely matched to the element called ozone, which led scientists to know that ozone is the element in the Earth's atmosphere that is absorbing ultraviolet rays. . Its properties were studied in detail by UK meteorologist GMB Dobson. He developed a simple spectrophotometer that could measure stratospheric ozone from the ground.
From 1928 to 1958, Dobson established a network of ozone monitoring centers around the world that function to date (2008). The convenient unit for measuring the amount of ozone is named the Dobson unit in Dobson's honor.