It refers to the currency with good international credit, stable value and strong status.
Hard currency and soft currency are only relative terms, it will change with the country’s economic and financial conditions.
Due to differences in the degree of inflation, international balance of payments and the degree of leniency among countries, when the inflation of a country is low, the value of its currency is relatively stable and the exchange rate is strong. In the international financial market, it is used to call it a hard currency.
Hard currencies, usually issued by highly industrialized countries, are widely accepted globally for trade payments. Their value remains stable in the short to medium term and they are highly liquid in the market.