All foreign currency assets owned by a country. It refers to the flow of money between countries and a specialized commercial activity of exchanging one country's currency for another country's currency to pay off international creditor's rights and debts. In fact, it is the creditor's rights held by the monetary management authorities (central bank, monetary management institutions, foreign exchange stabilization fund and Ministry of Finance) in the form of bank deposits, treasury bonds, long-term and short-term treasury bonds, etc. Can be used when the balance of payments is in deficit.