The banknotes and coins that you keep in your wallet have not always existed as you see them. What has always existed is the need to buy. This has led society to look for an element that fulfils the function that money currently occupies. What function does money have? Money can be defined as a set of assets in an economy, which people are regularly willing to use as a means of payment for the purchase and sale of goods and services.
To do this, in ancient times, a technique was used that we know very well: barter. This consisted of exchanging one merchandise for another, depending on its usefulness and value.