Here's why:

* Free Electrons: Metals have a unique structure where electrons are loosely bound to their atoms. These "free electrons" can easily move throughout the metal, allowing for the flow of electrical current.

* Good Conductivity: This free movement of electrons makes metals excellent conductors of electricity. They readily allow electrical charge to pass through them.

Insulators, on the other hand, resist the flow of electricity. Their electrons are tightly bound to their atoms, preventing easy movement and current flow. Examples of insulators include rubber, glass, and plastic.