Lens Hood

I received a lens hood with my Nikkor 55-200mm lens and decided to do some research on the uses/need of it. 
A lens hood or lens shade is a device used on the end of a lens to block the sun or other light source in order to prevent glare and lens flare.

Well, you are not required to use one, but if there are some very good reasons to do so.

The primary use for a lens hood is to prevent light from hitting the front lens element from the sides - reducing contrast and creating flare. Pictures taken with a lens hood installed will generally have richer colors, deeper saturation.

A secondary use for a lens hood is to protect the lens. The damage prevented can range from a finger-printed front element (a minor inconvenience) to a broken lens (possibly a major expense - and lost pictures). Lens hoods are generally strong and stick out from the lens some distance. Accidental touches and scratches to the front element are reduced simply because the glass is difficult to reach. Some impact protection is gained from having a sacrificial part taking the blow. Of course, ultra wide angle lenses have very short hoods that offer very little protection.

Lens hoods on longer focal length lenses offer some front lens element protection from rain and dust. The hood helps to keep the front element clean and dry. Of course, if your lens is not weather sealed, you should not let it get wet in the first place.

A small convenience tip: If the lens hood fits too tightly for your liking, add a little body oil to the threads. Your body oil - from your forehead, nose ... The hood will be much easier to twist on.

Get in the habit of always using a lens hood!