Clothing serves many purposes: it can serve as protection from the elements, rough surfaces, sharp stones, rash-causing plants, insect bites, by providing a barrier between the skin and the environment. Clothing can insulate against cold or hot conditions, and it can provide a hygienic barrier, keeping infectious and toxic materials away from the body. It can protect feet from injury and discomfort or facilitate navigation in varied environments. Clothing also provides protection from ultraviolet radiation. It may be used to prevent glare or increase visual acuity in harsh environments, such as brimmed hats. Clothing is used for protection against injury in specific tasks and occupations, sports, and warfare. Fashioned with pockets, belts, or loops, clothing may provide a means to carry things while freeing the hands.