What is the origin of money?

A number of objects have been used as money in the past, including certain sea shells or salt. Over time, commodity money, such as gold or silver coins whose value derived from their precious metal content, became widespread. Later on, commodity money gave way to paper money and representative money, whose value was backed by reserves of precious metals, meaning that people didn’t need to carry the previous metal coins on them. Paper money consisted of banknotes that could be exchanged for the stated amount of gold or silver. This form of money was used until the 20th century, when fiat money, based on trust, began to take hold in modern economies.