Why is the Ozone layer crucial to life on earth?

It blocks harmful UV (Ultra violet) rays that are harmful to creatures on Earth.Why is the Ozone layer crucial to life on earth?
High up in the atmosphere, 15-35 kilometers stratospheric ozone blocks harmful ultraviolet rays from the sun .Low in the atmosphere 0-5 kilometers, tropospheric ozone contibutes to smog and can be harmful to our breathing. It can damage lung tissue by making it brittle.Why is the Ozone layer crucial to life on earth?
It filters out the sun's UV rays so we don't get skin poisoning, or more global warming. Stuff like that.
It keeps the suns harmful rays from overheating the planet, and it also keeps oxygen from escaping.
the ozone layer is a particular part of the upper atmoshere that acts like the earths own sun-protection lotion and stops harmful radiation entering the atmosphere. unfortunately man-made chemicals such as CFC'c (used in packaging, spray paint can's, some fire extinguisher filled with (argon?) and refridgerator chemicals used as coolants such as R22 damage this layer. thats why they have been banned for years, but some damage has already been done
So we don't get roasted.
It has ozone molecules which block deadly radiation from the sun. Therefore, without an ozone layer, basically if you stepped outside you would probably get immediate sun burn and longer periods of time will result in skin cancer.
Ozone restricts the amount of solar rays hitting the planet. if there was no ozone, the temperature would rise so dramatically that the oceans would dry up and we would all die. Ozone (O3) is ';destroyed'; by chlorofluorocarbons (CFC's) which are found in aerosols, fridges etc. Also, there is no ';hole'; in the ozone layer, it is actually becoming thinner. (Just to clear up a common misunderstaning, no offence intended :D )