Fiat money
Fiat money is government issued currency. For example Euros (EUR), Dollars (USD), Pounds (GBP), Pesos, Rupees, etc.
It is centralized and controlled by governments. Fiat money is a tool of authority to extract value from people through inflation, seigniorage and the Cantillon effect. It is a tool of surveillance and population control. Governments rewards the most obedient with easy and early access to newly printed fiat money and punishes dissenters by blocking access to their accounts.
Fiat money has evolved from printed paper notes to digital accounts held at institutions granted government privilege or license to custody fiat money.
Fiat money is what you exit when you buy Bitcoin.
CBDC (Central Bank Digital Currency) is the final and most insidious form of fiat money, since as programmable money it allows a much higher degree of control, including geofencing, time limits, restrictions on saving, blacklisting, etc. It can potentially lead to ubiquitous law enforcement and facilitate social credit systems.