TL;DR: Don't use a UV filter. - Because it's not doing what you think it does.
Once you have a great camera, you may begin thinking about accessories for it. Or you may even encounter a camera salesperson who pushes you to buy all kinds of "necessary" options -- and salespeople can be pretty convincing. It can be hard to sort out what accessories are worth it and which ones are best to skip. One that falls into the "skip it" category for me is a UV filter, and I'll tell you why.
A UV filter's purpose is right there in the name: it keeps ultraviolet light out of your camera system. Ultraviolet light is high-energy light, and the human eye cannot perceive it. Film, however, is very sensitive to UV light. The closer you get to the equator, the more ultraviolet components the light will have. The light will be harder and harsher. Left unfiltered, this will result in bluish, hazy photos. IF you have a film camera. By all means, if you are using a film camera, and especially if you're going to be photographing in the equatorial latitudes, use a UV filter.
Most of us, though, are not using film cameras. They have been mostly replaced by digital cameras, and digital cameras are a whole different story when it comes to ultraviolet light. The chips in digital cameras are most sensitive to light at the exact opposite end of the spectrum: infrared light. So much so, in fact, that in order to make cameras operate in the range of light that the human eye can see, manufacturers build an infrared filter into their cameras. In other words, digital cameras need to be modified to make chips sensitive enough to visible light to capture an image in the first place. Digital cameras cannot even perceive ultraviolet light, and so they certainly do not need a filter to screen it out.
Some people might tell you that even though a digital camera doesn't need to have ultraviolet light filtered out, a UV filter is still necessary to protect the lens from direct sunlight exposure. This may sound like a good idea, and I won't argue that protecting your lens is a good idea. What I will argue, however, is that a lens hood is a better choice than a UV filter. The lens hood protects your lens by keeping light from hitting the first layer of glass. This eliminates lens flares in your images. A lens hood also provides a physical barrier that can help protect your lens from scratches and accidental bumps. I suppose a UV filter would do that, too, but remember that a lens hood is often included at no extra charge with a lens, whereas a UV filter is a separate accessory. And if a lens hood gets scratched, it's not too big a deal. If a filter that fits on the front of your lens gets scratched, or heavens forbid, broken, it will no longer be usable and might end up damaging your lens. That happened to me a long time ago when I was still using film.
