The Cokin 37mm Digi-Hood is a small-diameter metal lens hood that is specifically designed for use with compact digital cameras or camcorders that feature filter threads. It screws directly into the filter threads at the front of the lens or filter adapter (if available).
Lens hoods are primarily designed to prevent unwanted stray light from entering the lens by extending and shading the end of the lens, thus eliminating flare. In addition, since the end of the lens is extended, you also get the added benefit of some extra protection from accidental impact.