Conductors

* Metals: Copper, Silver, Gold, Aluminum, Iron, Mercury, Brass, Bronze

* Electrolytes: Saltwater, Acidic solutions, Basic solutions

* Semiconductors: Silicon, Germanium, Carbon (graphite)

* Plasma: Ionized gases

Insulators

* Nonmetals: Rubber, Glass, Plastic, Wood, Air, Paper, Porcelain, Mica, Diamond

* Ceramic materials: Silica, Alumina, Zirconia

* Gases: Oxygen, Nitrogen, Argon, Helium, Neon

* Vacuum: A near-perfect insulator

Note: This list is not exhaustive, and the conductivity of materials can vary depending on factors like temperature, pressure, and impurities.