This is a component which can be mounted in front of the lens with the purpose of changing the direction of oblique sun rays that can affect image clarity. They have to correspond with the lens type.
Lens-hood’s are very useful in sunny days but also in cloudy days. They are used especially when photographing the sun, mirrors, windows, waters, reflecting surfaces etcetera. They prevent any direct or indirect light to come into contact with the lens surface, thus, eliminating the glare effect in the images.