A feature of nearly all human societies is the wearing of clothing or clothes, a category encompassing a wide variety of materials that cover the body. The primary purpose of clothing is functional, as a protection from the elements. Clothes enhance safety during activity by providing a barrier between the skin and the environment. Clothing also acts as a hygenic barrier, keeping toxins away from the body and limiting the transmission of bacteria and viruses. Outside of their purely functional purpose, clothes often play an important social and cultural role. Most societies develop norms about modesty, religious practices, behavioral appropriateness, social status, and even political affiliations in which clothes play an important role. Finally, clothing functions as a form of adornment and an expression of personal taste or style.