Which of these types of materials readily allows the flow of electric current?

A conductor is a material that contains free electrons, allowing electrical current to pass through it easily. Metals like copper, silver, and gold are excellent examples of electrical conductors. In contrast, an insulator (also known as a dielectric) strongly resists the flow of electricity. Semiconductors fall in the middle, only allowing current to flow under specific conditions, which is why they are used to build transistors and diodes rather than wires.