Copper coins are small, round pieces of metal that are primarily made of copper or copper alloys. They have been used as currency for thousands of years, dating back to ancient civilizations. Today, many countries still produce copper coins, although they often contain a mix of metals to reduce costs and improve durability. In the United States, for example, the penny is a well-known copper coin, originally made of nearly pure copper. Over time, its composition changed to include zinc, making it less expensive to produce while still retaining its distinctive reddish-brown color.