Substances which do not allow electricity to pass through them easily are called insulators. These are made from materials which have a high resistance. Some substances which are insulators are air, plastic, cotton, rubber, wood, paper, glass, pure water, etc.
Substances which allow electricity to pass through them easily are called conductors. These are made from materials which have low resistances. Some examples are metals like copper, aluminium, silver, iron, brass and also salt solutions.
