What is the purpose of uv filters?

I recently got nikon d90 and people have told me get an uv filter but i can't quite understand it's purpose. Can somebody please tell me the advantages of having an uv filter and also what will happen to my camera if i don't have an uv filter.

The purpose of a UV filter on a digital camera is to increase the revenue of the store that sells it. The people who told you that it will protect your lens front element either don't know what they're talking about or are making money from selling filters. Keep the lens cover on when you're not shooting. Use a lens hood when you are. It protects the front element and has the added benefit of actually improving your shots, while a filter can only degrade them.

I usually agree with Hondo, but in this case I don't

Keeping sticky fingers off the front element reduces the number of times you have to clean the front element of the lens. Each cleaning removes a tiny portion of the special lens coating that reduces the possibility of lens flare or ghosting.

But here is evidence of how a UV can protect a lens.

This $60 lens saved a $700 lens

Some people claim it will offer the front of your lens some protection. It won't. Any knock strong enough to damage the thick glass on the front of your lens is more than strong enough to break a super thin UV filter. The result will just be broken UV filter glass all over the front of your lens. Buy a lens hood for your lens instead. That will help you control flair, and offer protection to the front of your lens without adding additional glass.

If you are shooting in blowing sand or water, a UV filter would be a good idea. In any other situation they are a waste of money that could degrade image quality.

Take fhotoace's picture for example. He presents this photo frequently as evidence of how a UV filter can save a lens. However, a quick look shows that the impact was clearly to the SIDE of the lens and lens hood, NOT the front where the UV filter could do some good. It is not possible that the UV filter provided impact protection to the side of the lens. Instead, his UV filter shattered and sprayed the front of his lens with shattered glass, and in doing so offered no protection whatsoever. If he had been using only the lens hood, it would have provided the same amount of protection as the UV filter (since the impact was to the side of the lens), and he would not have shattered glass all over his lens.

I always thought a uv filter was to correct for the slightly bluish hue you could get from UV rays. But maybe I'm wrong.