Thermal socks are socks that are designed to keep your feet warm in cold weather. They are usually made from materials that have good insulation properties, such as wool or synthetic fibers, and may also have a thick or padded construction to provide additional warmth. Thermal socks are often worn as an extra layer of insulation under regular socks or shoes, especially in cold or wet outdoor conditions. They can be a helpful addition to your winter wardrobe if you live in a cold climate, or if you participate in outdoor activities such as skiing, snowboarding, or hiking.