Lens hood offers several benefits to the photographer. Primarily the hood shades the lens from stray light that may result in an unwanted discoloration or hazing of the image, or the appearance of lens flare; shading your lens helps improve contrast and image quality. Also it offers limited protection from keeping moisture and wind blown debris off the from lens element and adds extra protection from accidental impact.
Designed for Canon EF 28-80mm f/3.5-5.6 II, EF 28-90mm f/4-5.6 II, EF 28-90mm f/4-5.6 III, EF 28-90mm f/4-5.6 USM, EF-S 18-55mm f/3.5-5.6, EF-S 18-55mm f/3.5-5.6 IS II and EF-S 18-55mm f/3.5-5.6 USM lensesDesigned to prevent unwanted stray light from entering the lensEnsures no problems with vignetting or motor functionsAdded benefit of extra protection from accidental impact