The practical function of clothing is to protect the human body from dangers in the environment: weather (strong sunlight, extreme heat or cold, and precipitation, for example), insects, noxious chemicals, weapons, and contact with abrasive substances, and other hazards. Clothing can protect against many things that might injure the naked human body. In some cases, clothing protects the environment from the clothing wearer as well (example: medical scrubs).

Humans have shown extreme inventiveness in devising clothing solutions to practical problems and the distinction between clothing and other protective equipment is not always clear-cut; examples include space suit, air conditioned clothing, armor, diving suit, swimsuit, bee-keeper's protective clothing, motorcycle leathers, high-visibility clothing, and protective clothing.

People also decorate their bodies with makeup or cosmetics, scented perfume, and other ornamentation; they also cut, dye, and arrange the hair on their heads, faces, and bodies (see hairstyle), and sometimes also mark their skin (by tattoos, scarifications, and piercings). All these decorations may contribute to the overall effect and message of clothing, but do not constitute clothing.

Articles carried rather than worn (such as purses, canes, and umbrellas) are normally considered fashion accessories rather than clothing, but hats and small dress sweaters can be called clothing or accessories.[citation needed] Jewelry and eyeglasses are usually considered as accessories as well,[citation needed] even though in common speech these particular items are described as being worn rather than carried.

Historically, there have been many societies where partial or complete nudity was the cultural norm. In the modern world, most cultures find it socially unacceptable to walk around in public without clothes.