Since charge can move through electrical conductors, a conductor must remain neutral. Some of the outermost electrons in the atoms of the conductor are free to move. The atoms of an electrical insulator are characterized by tightly bound orbiting electrons. An object made of an insulating material cannot hold a net electrical charge. Insulators cannot become polarized.
Insulators have very low electrical resistance.
A ball is suspended by a thread. When we bring a rod close to the ball, the ball is attracted towards the rod. Both the ball and the rod are both positively charged. Both the ball and the rod are both electrically neutral. Both the ball and the rod are negatively charged.