Why do some metals, like gold and copper, conduct electricity so well?

In metals, electrons are not tied to one atom the way they are in many nonmetals; they move through a shared 'sea' of electrons. This makes it easy for electric current to flow when a voltage is applied. Copper is widely used in wiring because it combines excellent conductivity with relatively low cost and durability, while gold is also a superb conductor and resists corrosion. Silver conducts even better than copper, but it is less practical for many uses because of price and tarnish concerns.