SavvySox What Are Those A sock is an item of clothing worn on the feet and often covering the ankle and some part of the calf. Some type of shoe or boot is typically worn over socks. In ancient times, socks were made from leather or matted animal hair. In the late 16th century, machine-knit socks were first produced. Until 1800 both hand knitting and machine knitting were used to produce socks, but after 1800, machine knitting became the predominant method. One of the roles of socks is absorbing perspiration. The foot is among the heaviest producers of sweat in the body, as it can produce over 0.25 US pints (0.12 l) 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 made from wool insulate the foot and decrease the risk of frostbite. Socks are worn with sport shoes (typically white-coloured socks) and dress shoes (typically dark-coloured socks). In addition to the numerous practical roles played by socks, they are also a fashion item, and they are available in myriad colours and patterns. Socks have evolved over the centuries from the earliest models, which were made from animal skins gathered up and tied around the ankles. In the 8th century BC, the Ancient Greekswore socks from matted animal hair for warmth. The Romans also wrapped their feet with leather or woven fabrics. By the 5th century AD, socks called "puttees" were worn by holy people in Europe to symbolize purity. By 1000 AD, socks became a symbol of wealth among the nobility. From the 16th century onwards, an ornamental design on the ankle or side of a sock has been called a clock. The invention of a knitting machine in 1589 meant that socks could be knitted six times faster than by hand. Nonetheless, knitting machines and hand knitters worked side by side until 1800. The next revolution in sock production was the introduction of nylon in 1938. Until then socks were commonly made from silk, cotton and wool. Nylon was the start of blending two or more yarns in the production of socks, a process that still continues.