Currency): commonly known as hard currency or strong currency. Refers to the currency with stable currency value, firm and freely convertible exchange rate, rising exchange rate and good credit in the international foreign exchange market, which can be used as an international means of payment or circulation. Mainly: US dollars, British pounds and Japanese yen.

Soft Currency (soft currency or Soft Money or Weak

Currency): commonly known as soft currency or weak currency. It refers to the national currencies with relatively unstable currency value, weak exchange rate, inability to freely exchange other countries' currencies, unstable exchange rate with downward trend and low credit degree in the international foreign exchange market, mainly including Indian Rupee and Vietnamese dong.

Hard currency and soft currency are relative concepts, which change with the change of a country's economic and financial situation. For example, the US dollar was a hard currency in the 1950s and became a soft currency in the late 1960s and 1970s. Since the 1980s, the US dollar has once again become a hard currency.

Commodity currency (commodity currency or block

Currency): When a country is rich in raw material resources, and raw materials account for the bulk of its exports, its economy will be closely linked with the price of raw materials, and its currency will also change in the same direction as the price of raw materials, and it will be considered as a commodity currency. Therefore, whenever the linked raw material prices rise, the currency prices of these countries will rise accordingly; On the contrary, whenever the linked raw material prices fall, the currency prices of these countries will fall accordingly.