An explanation of the term Fiat currency below:
Fiat money is money that has value only because of government regulation or law. The term derives from the Latin fiat, meaning "let it be done", as such money is established by government decree. Where fiat money is used as currency, the term fiat currency is used.
Fiat money originated in 11th century China,[1] and its use became widespread during the Yuan and Ming dynasties.[2] The Nixon Shock of 1971 ended the direct convertibility of the United States dollar to gold. Since then all reserve currencies have been fiat currencies, including the dollar and the euro.
Buying Gold is a way of hedging your currency. Put simple, no matter what happens to money, Gold is a precious metal that will always retain a level of value which is not regulated by government. This is why many invest a portion of their investment in gold.