By Anne Marie Helmenstine, Ph.D. A material that readily transmits energy is a conductor, while one that resist energy transfer is called an insulator. There are different types of conductors and insulators because there are different forms of energy. Materials that conduct electrons, protons, or ions are electrical conductors. They conduct electricity. Usually, electrical conductors have loosely bound electrons. Materials that conduct heat are thermal conductors. Substances that transfer sound are acoustical conductors. There are corresponding insulators for each type of conductor.