Insulators are materials which prevent the flow of heat (thermal insulators) or electric charge (electrical insulators). The opposite of electrical insulators are conductors and semiconductors, which permit the flow of charge.

Electical Insulators prevent undesired flow of electricity. They are made of materials such as plastic, quartz, ceramics, glass, porcelain and silicon that do not conduct current. Charge on an insulator will not distribute itself over the material's entire surface, but will stay fixed at the generating site.