Lens hoods are awesome things for your camera. They do quite a few things to help your photography as well as protect your lens.
Most lenses you buy for your DSLR will come with a lens hood. When i first got one, i thought they looked funny and had no idea what to do with it, so i tossed it in my camera box and forgot about it. As time went on i realized how useful they were. If you camera didn’t come with one you can buy them in any ring size ( the size of your lens ) on-line at places such as Amazon, Adorama, or B&H Photo.
First off they protect your lens in more ways then one. They keep little fingers from touching your lens. I cant tell you how many times one of my children has picked up my camera, or tried to touch the glass in my lens. Having a lens hood deflects those fingers so no one puts fingerprints on my lens or scratches it.
They also protect the glass from being scratched or broken if you happen to drop your camera or lens. It happens more often then you think. Someone grabs the camera strap. Or in my case i had too much in my arms and almost dropped my baby, instead i dropped my camera and shattered my lens hood, but didn’t hurt my lens. Thankfully.
They also help with taking pictures. A lens hood protects against flaring. This happens when you point your camera too close to your light source ( such as the sun ). You probably know it, you took a picture in the evening and the image looks odd, sort of foggy with golden light, or has lighter spots spattered across the photo. All are effects of a flare from the sun. Having a lens hood will prevent that flaring. In a pinch using your hand works but often enough your fingers end up in the frame as well. A lens hood, attached to the end of your lens will keep the light from speckling.
And purely for looks, they make your lens look bigger. In the world of the bigger lenses the most attention giving an extra inch or two to your lens can be a fun thing to do. Now it doesn’t make your camera take better close ups. But it makes the lens look larger.
There are several kinds of lens hoods. A solid lens hood, which is a sold ring or plastic. A flower lens hood, which has what looks like petals coming out. A collapsible lens hood, which you can pull out and push down as needed. They also come in various lengths. From just a short little ridge, to several inches long. Its up to you to decide how long of a hood you like to have.
While you don’t absolutely have to have a lens hood, they do make a difference. If you drop your camera, you are less likely to shatter the lens. It keeps fingers off of the lens and will prevent flare from spattering across your images. They are a worthy investment and because they are pretty inexpensive you can grab one for every lens.