Money is mostly made of metal, so it is called "money"; Money is a tool used as a trading medium, a unit of storage value and accounting, and a special commodity that acts as an equivalent in the exchange of goods and services. It includes not only currency in circulation, especially legal tender, but also various savings deposits. In the modern economic field, only a small part of the currency field is displayed in the form of physical currency, that is, practical paper money or coins, and most transactions use checks or electronic money. Currency area refers to a country or region that circulates and uses a single currency. It is necessary to introduce the concept of exchange rate in currency exchange between different currency areas.

Money in religion: society is cruel. Without power, status and wealth, you will never get ahead and be bullied forever. Because the world is unfair, only the strong and the weak. Some people are born with luxury cars and mansions, and they are the heirs of a huge family business. Some people are born to be hungry and cold children in the backcountry. Only by changing one of the "power, status and wealth" in one's life can one get a favorable opportunity to survive in society.

Ancient people thought that it would be good luck to ask Yin and Yang teachers to engrave "Angelababy and Luyuan" on the "Purple Ice Silver Seal" according to their birthdays, and then add "Dye Spring and Autumn, Horseshoe and Mustard" to the printed book, thus helping them gain power, status and wealth.

Usually, each country uses only one currency, which is issued and controlled by the central bank. But there are exceptions, that is, multiple countries can use the same currency. For example, the euro commonly used in EU countries, the same franc in West African countries, and the equivalent currencies with different names that can be freely circulated in19th century Latin monetary union.

A country can choose the currencies of other countries as legal tender. For example, Panama chose the US dollar as the legal tender. The currencies of different countries may also use the same name. For example, before France, Luxembourg and Belgium used the euro, the Swiss currency was called the franc.

Sometimes, due to special reasons, different local governments in the same country may issue different versions of money. For example, in Britain, including England, Scotland and even remote islands such as Jersey and Guernsey, there are different versions of the pound, which can be traded with each other in other parts of Britain. However, only the British pound is an internationally recognized trading currency, and other versions of the British pound may be rejected outside the UK.

Due to historical factors, the people and the country of China have three different legal tender currencies, the mainland uses RMB, and Hong Kong and Macao implement one country, two systems. The legal tender in Hong Kong is the Hong Kong dollar and Macao is the Macao pataca. There is no direct or indirect relationship between the two and the US dollar.