Just about all my lenses are fitted with lens hoods. Some either came with them, as in the case of the Sigmas. And some hoods I had to purchase separately as Canon does not ship their entry level lenses with them. Lens hoods serve a few purposes. First and foremost they block out unwanted light and can improve saturation of a photo. Think of a being outside on a bright sunny day with out anything covering your eyes. Then being out on a bright sunny day then putting a ball cap on, how it makes looking at things easier. Or sometimes you even put your hand up to your brow. The same thing happens with using a lens hood. Sometimes you catch the sun when taking a pic and get unwanted flaring across your subject, a lens hood can help you avoid that. Another thing a lens hood can help do is protect the lens. Now this isn’t technically the purpose but it does help. Now I don’t normally use any kind of filters on my lenses. Its just my preference, I prefer to shoot with out them. So the element on the front is always exposed to everything. Having a hood on keeps my fingers away from the lens. I don’t use a conventional neck strap, I use a shoulder strap that lets me hang the camera at my side. Sometimes I’m reaching blindly and it helps keep my fingers off the glass. There was another time I was climbing up some rocks and my camera swung around and hit one. The edge of the hood took the nick and not the lens. If you are on a budget or not it is a good accessory to have. Factory ones are in the $30-$35 range while you can pick up aftermarket (what I use ) for $12-$18.