A sock is an item of clothing worn on the feet. The foot is among the heaviest producers of sweat in the body, as it is able to produce over 1 USpt of perspiration per day. Socks help to absorb this sweat and draw it to areas where air can evaporate the perspiration. In cold environments, socks decrease the risk of frostbite

Frostbite

Frostbite is the medical condition where localized damage is caused to skin and other tissues due to extreme cold. Frostbite is most likely to happen in body parts farthest from the heart and those with large exposed areas...

. Its name is derived from the loose-fitting slipper, called a soccus in Latin, worn by Roman comic actors.
Socks have evolved over the centuries from the earliest models which were made from animal skins gathered up and tied around the ankles.