Copper is a reddish-gold colored metal that's commonly used in electrical wires and plumbing. Your grandmother might make her famous chocolate caramel sauce in a shiny copper pot.
Before 1983, pennies were 95 percent copper. Today, they're almost entirely zinc (a less expensive metal), coated with a thin copper plating. They look the same, but the older coins are quite a bit heavier. Copper is a good conductor of heat and electricity, which is why it's used for both fancy cookware and wires. You can also use copper for things that have a similar color: "His copper curls make him stand out from the other choir members."