Fiat currency

Fiat currency = any National currency not backed by a physical commodity. Fiat currency is on the market as: coins, banknotes and electronic form. Fiat currency is also called 'fiduciary' currency (in Latin: fides means belief) - as there is a belief embaded to the Issuer, that currency reflects its tangible value in real life transactions.

Have you known that British sterling is the oldest currency in circulation?

The British pound sterling is the oldest currency still in circulation today, dating all the way back to 800 when it took the form of silver pennies. The nickname "pound" originates from the measuring system first used to value the coins. At the time 240 sterling coins weighed one pound⚖ . Today one pound is divided into 100 pence, and the currency is represented by paper banknotes and £1 and £2 coins.

The British pound sterling is 4th most traded currency on the forex marketplace. It features heavily in major, minor and exotic currency pairs. Like most modern major currencies, the pound is heavily influenced by monetary policy from the Bank of England, inflation, UK economic growth and trader sentiment.

The most popular currency pair featuring the pound, GBP/USD, often moves similarly to EUR/USD. However, GBP/USD is negatively correlated, meaning it usually moves opposite to, with EUR/GBP.

Source: https://www.forex.com/en-us/news-and-analysis/what-is-the-oldest-currency-in-the-world/