The buying and selling of goods and services within a country is known as internal trade.
Internal trade refers to the exchange of goods and services between individuals, businesses, and organizations within the borders of a country. It involves the transfer of goods and services from producers to consumers or from one business to another within the same country.
For example, when you go to a local store to buy groceries or when a company sells its products to customers within the country, it is considered internal trade.
Internal trade is an essential part of a country's economy as it enables the circulation of goods and services within the country, stimulates economic growth, creates job opportunities, and fulfills the needs and wants of the people.
International trade, on the other hand, refers to the exchange of goods and services between different countries. Barter is a system of trade where goods or services are exchanged directly without the use of money. Foreign trade specifically refers to the trade between different countries or the import and export activities of a country.
Therefore, in this context, the correct term for the buying and selling of goods and services within a country is internal trade.