What is the Ozone Layer? What is the significance? Why do we protect it? How do we know what we know about it)

ozone layer is just about 900 km away from earth surface . It helps us to protect earth from ultra violet rays from sun . i don't know which scientist found ozone layer but we protect it cuz once the ultra violet rays reaches earth and there is no ozone layer you don't want tosee your hand getting roasted .