Knee length socks goes over or up to the knee. They are basically worn while playing sports or during the winter seasons. During harsh winter you can wear them at home to keep your feet warm. Knee length socks are a little expensive than other socks because of the extra material on it to make it as long as knee. Knee length socks are also worn by men in the British army and navy, it is part of their uniform to protect them in the trenches.