Lens flare spoils many pictures. Even when it does not show as a streak across the image, it can cause overall loss of contrast. Flare is caused by light from bright sources - such as the sun or spotlights - hitting the front element of the lens at an angle. This sets off a series of unwanted internal reflections and refractions. This genuine Canon lens hood protects the front of the lens from this side lighting.
Lens hoods are shaped specifically for the type of lens. Some are straight, some are petal-shaped. They can also be reversed on the lens for storage.
This lens hood fits the following Canon lenses:
EF-S 10-18mm f4.5-5.6 IS STM