Materials that allow electric current to pass through them are called
conductors. A conductor is a material which contains movable electric charges. In easy words Conductors are materials that pass electrical current easily, that is, with low resistance.
Conductors are ordinarily metals. Some examples of conductors are: Silver, Copper, Carbon, and Aluminum etc.
Insulators are materials that do not pass electrical current easily, that is, they have high resistance. Insulators are materials that have just the opposite effect on the flow of electrons. They do not let electrons flow very easily from one atom to another. Insulators are materials whose atoms have tightly bound electrons. These electrons are not free to roam around and be shared by neighboring atoms. An insulator, also called a dielectric, is a material that resists the flow of electric charge. In insulating materials valence electrons are tightly bonded to their atoms. These materials are used in electrical equipment as insulators or insulation.
It must be understood that not all conductive materials have the same level of conductivity, and not all insulators are equally resistant to electron motion. Electrical conductivity is analogous to the transparency of certain materials to light: materials that easily “conduct” light are called “transparent,” while those that don’t are called “opaque.” However, not all transparent materials are equally conductive to light. Window glass is better than most plastics, and certainly better than “clear” fiberglass.Some examples of insulators are Glass, Nylon, and Wood etc.