The materials or substances that resist or don't allow the current to pass through them are insulators. They are, in general, solid in nature. Insulators are often used in a number of places as they do not allow heat to flow. Their resistivity is the property that makes insulators different from conductors.Some good examples of insulators are wood, fabric, glass, mica, and quartz. Insulators are protectors as well. They provide protection against fire, sound, and, of course, electricity transmission. In addition, insulators have no free electrons at all. This is the predominant explanation of why electricity cannot pass through these materials. Examples of Insulators are Glass, Plastic, wood