Insulators are materials that inhibit the flow of electrical current. The opposite of conductors, which allow electric particles to flow freely, insulators are implemented in household items and electrical circuits as protection. Thermal insulation is similar, but it constricts the flow of heat rather than electricity.
Insulators possess a high resistivity and low conductivity. Their atoms have tightly bound electrons that do not move throughout the material. Because the electrons are static and not freely roaming, a current cannot easily pass. In addition to protecting loss of current, insulators make an electrical current more efficient by concentrating the flow.
The opposite of an insulator is a conductor--a material with a low resistance and a high conductivity to electrical current or heat. Metals are considered conductors because their electrons are not tightly bound, allowing the flow of both electricity and heat. Copper is the most widely used conductor of electricity in wires, but almost any metal will conduct electricity to some degree. Water and most liquids are conductors as well.
Glass was one of the first materials used in electrical transmissions but has been largely replaced in favor of cheaper materials. Glass and porcelain are commonly used for high-voltage transmissions. Plastics have a lower resistivity than glass but are more practical for mass usage. They are adequate insulators for wiring and cables. Wood is also a good heat insulators; both plastics and wood are used on the handles of cookware and other household items, such as irons.
In buildings, insulation is the material used to prevent the transfer of heat. Properly insulating a house helps to make it energy-efficient, saving the owner money. Insulation materials for buildings range from concrete blocks to mats of synthetic fibers. Plastic films are used to cover windows to further prevent the transfer of heat. Insulation is generally put into the walls and attic of a home.