Here's why:

* Conductors allow electricity to flow easily through them. Copper has free electrons that can move easily, carrying electrical current.

* Insulators resist the flow of electricity. They have tightly bound electrons that don't move easily. Examples of insulators include rubber, plastic, and glass.

The insulation on a copper wire is an insulator, typically made of materials like plastic or rubber. Its purpose is to prevent the electrical current from flowing outside of the wire, protecting people and equipment from electric shock.