1. Commodity money: This was the earliest form of money and consisted of valuable commodities such as gold, silver, copper, and salt. These commodities had intrinsic value and were widely accepted as a means of exchange.
2. Fiat money: Fiat money is currency that is not backed by any physical commodity but is instead issued by a government or central bank. Its value is determined by the trust and confidence that people have in the issuing entity. Fiat money became more common in later periods of history.
3. Coins: Coins are small, flat, usually round pieces of metal stamped with a design or symbol that indicates their value. They were made from precious metals like gold and silver and were widely used in ancient civilizations such as Greece, Rome, China, and India. Coins made it easier to carry and exchange money.
4. Banknotes: Banknotes are paper money issued by banks or governments. They are not backed by any physical commodity but represent a claim on the issuer to pay the bearer a certain amount of money. Banknotes became more prevalent in the 17th and 18th centuries, gradually replacing coins as the dominant form of currency.
The appearance and materials used for money varied across cultures and time periods, but these different forms of money facilitated trade, commerce, and economic activities in ancient times.