An insulator exhibits a large resistance to the flow of electricity. A conductor exhibits a small resistance to the flow of electricity. Both insulators and conductors are essential to the operation of electrical and electronic circuits. Conductors carry electrical currents along the chosen paths in the circuit and insulators are used to separate these paths and protect them from external influences.
In materials such as glass, electrons have very little freedom to move from one atom to the next. While external forces such as physical rubbing can force some of these electrons to leave their respective atoms and transfer to the atoms of another material, they do not move between atoms within that material very easily.
There are many materials that have insulating properties, including glass, rubber, oil, ceramic, quartz, plastic and air.
With some types of materials, such as metals, the outermost electrons in the atoms are so loosely bound that they drift in the space between the atoms of that material under the influence of electrical fields.
There are many materials that have conductive properties, including silver, copper, gold, aluminum, iron, steel, brass and bronze.
Power Distribution Grid
The power distribution grid consists of conducting cables suspended between tall steel towers. The cables are insulted from the towers by large glass insulators.
Domestic house wiring consists of insulated copper conductors carrying the circuit current between the various components within the system.
An electronic printed circuit board (PCB), consists of an insulated base board upon which conductive tracks carry the circuit currents between the various components.