The ability to transmit heat or electricity is called conductivity. Thermal conductors are items that are conducive to conducting heat, while electrical conductors are items that easily conduct electricity.
Metals and alloys are more conductive than any other materials. The metal with the highest known electrical conductivity is silver, and it is the standard by which the conductivity of other elements is measured. Substances that are conductive often relay both heat and electricity. Products that are not conductors, or semi-conductors in some cases, are known as insulators. Wood, polymers, rubber and glass inhibit the passage of both electricity and heat.