Sock is also the term given to the layer of leather or other material covering the insole of a shoe. When only part of the insole is covered, leaving the forepart visible, this is known as a half-sock.
Socks are designed for wear with footwear that covers the entire foot (or feet), such as athletic shoes, boots, or dress shoes. They are sometimes worn with open-toed shoes, such as sandals. Socks are also frequently worn without shoes, typically indoors.
The average foot has 250,000 sweat glands, and the average pair gives off about half a pint (almost 250 mL) of perspiration per day. Socks help to absorb this sweat and draw it to areas where air can wick the perspiration away. In cold environments, socks help to remove the moisture given off by one's feet, decreasing the risk of frostbite.