Coins of the United States dollar were first minted in 1792. New coins have been produced annually since then and they make up a valuable aspect of the United States currency system. Today, circulating coins exist in denominations: $0.01, $0.05, $0.10, $0.25, $0.50, and $1.00. Also minted are bullion (including gold, silver and platinum) and commemorative coins. All of these are produced by the United States Mint. The coins are then sold to Federal Reserve Banks which in turn are responsible for putting coins into circulation and withdrawing them as demanded by the country’s economy.
Article Source: en.wikipedia.org