* Silver: Excellent conductor of electricity. It's actually the best conductor of all metals.

* Rubber: A very poor conductor of electricity. It's an insulator.

* Glass: A poor conductor of electricity. It's also an insulator.

* Plastic: Generally a poor conductor of electricity. Most plastics are insulators. However, there are some specialized plastics that can conduct electricity.

Key Concepts:

* Conductors: Materials that allow electricity to flow easily through them.

* Insulators: Materials that resist the flow of electricity.

In summary: Silver is the best conductor of electricity from the list, while rubber, glass, and most plastics are insulators.