Fiberglass insulation, Styrofoam and the down panels in winter jackets are all examples of strong thermal insulators that work to keep temperature consistent and retain internal heat while preventing temperature exchange. Thermal insulators work by trapping air, which does not conduct heat well or efficiently, and using it as a buffer between zones.
Thermal insulators can help to keep a space cool as well as warm. When the outside air is hot, the air trapped in a thermal insulator makes it harder for that heat to exchange with the interior insulated space whether it is a house or a person wearing insulated clothes. Heat building up inside the insulated environment can, however, supersede this effect.
Common uses of thermal insulators include regulating body temperature and regulating the temperature of food and beverages. Thermoses are designed to keep soup hot by preventing it from engaging in temperature exchange with the air and the outside climate, while coolers insulate food for the opposite reason.
Wood and plastic also function as thermal insulators because they are generally very poor conductors, making them similar to air and other gases in that regard. They are sometimes used as parts of machinery to regulate temperature and to keep exchange between internal and external environments under control.