Reasons for the exchange rate: The currencies of different countries can be compared with each other and form a price relationship because they all represent a certain amount of value, which is the decisive basis of the exchange rate. Under the gold standard, gold is the standard currency. The monetary units of two countries that implement the gold standard can determine the exchange rate between them according to their respective gold contents. For example, when the gold coin standard system was implemented, Britain stipulated that the weight of 1 pound was 123.27447 grains, and the fineness was 22 karats, that is, the gold content was 1 13.005438+06 grains of pure gold; The United States stipulates that 1 USD has a weight of 25.8 grains and a purity of 900 thousandths, that is, pure gold with a gold content of 23.22 grains. According to the comparison of the gold content of the two currencies, the exchange rate fluctuates on the basis of 1 =4.8665 USD. Under the paper money system, countries issue paper money as the representative of metal money. According to the past practice, the gold content of paper money is stipulated by the French exchange rate order, which is called gold parity. The comparison of gold parity is the decisive basis for the exchange rate between the two countries. However, paper money cannot be converted into gold, so the legal gold content of paper money often exists in name only. Therefore, in countries where the official exchange rate is implemented, the exchange rate is set by the national monetary authorities (Ministry of Finance, Central Bank or Administration of Foreign Exchange), and all foreign exchange transactions must be conducted according to this exchange rate. In countries that implement market exchange rate, the exchange rate changes with the change of money supply and demand in the foreign exchange market. The exchange rate has an impact on the balance of payments and national income. The exchange rate is regulated by the state: since the US dollar is the world currency, all countries basically use the US dollar as the benchmark for currency exchange. When it is necessary to adjust their own exchange rate, they will sell or buy their own currency in the international market and buy or sell equivalent US dollars to achieve the purpose of adjusting the exchange rate.