Lens caps are protective covers used to shield the front and rear elements of camera lenses from dust, scratches, moisture, and other potential damage. Typically made of plastic or metal, lens caps fit securely over the lens to prevent exposure to harmful environmental elements when the lens is not in use. There are two types of lens caps: front caps, which cover the glass of the lens, and rear caps, which protect the mount area that connects the lens to the camera body.