Many photographers use lens hoods when taking photographs. The lens hood helps block out the sun, which can cause an unwanted flare in what would have been a perfect shot. Canon makes lens hoods for almost all of its lenses, depending on the type and size of lens. The hoods are very easy to connect to the lens.
Attach the lens to the camera body by aligning the red dot on the lens with the red dot on the camera body. If it is an EF-S lens, you will be attaching the white square to the white square instead of red dots.
Align the red dot on the lens hood with the red dot on the end of the lens. The red dot is the same on all lens hoods, regardless if it is an EF lens or an EF-S lens.
Turn the lens hood clockwise until it locks into place. The red dot on the camera should align with the line and circle on the lens hood. The lens hood is now connected to the camera lens.