Long underwear, often called long johns, is a style of two-piece underwear with long legs and long sleeves that is normally worn during cold weather. It offers an advantage over the union suit in that the wearer can choose to wear either the top, bottom, or both parts depending on the weather. Long underwear are also less commonly known as "long handles".
Modern long underwear has largely supplanted the one-piece union suit. In the USA, it is usually made from a cotton or cotton-polyester blend fabric with a box-weave texture, although some varieties are also made from flannel, particularly the union suit, while many newer varieties are made from polypropylene, such as the Capilene trade name.