In general, metals like copper and aluminum are the best conductors of electricity. Good conductors are able to allow electrons to easily flow through.
Metals are typically good conductors because of their ability to donate electrons. Most metal atoms have one or two valence electrons, which means that they want to give these away in order to become more stable. When electrons are introduced, they are quickly passed through the chain of metal atoms.
Conductors are so-named because they permit the flow of electricity, or the movement of electrons from one atom to another. While metallic substances make good conductors of electricity, non-metallic substances usually do not. These include air, glass, wood, plastic and rubber. Materials that are not good conductors of electricity are commonly known as insulators. Insulators restrict the flow of electrons from one atom to another. Some of the strongest insulators include glass, pica and quartz. Insulators are used where it is necessary to protect or shield from electricity, such as electrical cords. The covering of the cord is the insulator, which prevents electricity from flowing to the outside of the cord. The inside of the cord contains the conductor, which allows electricity to flow and the appliance to function.The relationship between conductors and insulators can be summarized in terms of their resistance to electrical current. Conductors have low resistance to electrical current. Insulators have high resistance to electrical current.
The opposite of conductors are insulators, which either prevent or heavily limit the flow of electrons. These are typically made out of non-metal materials like glass.