Tariff is an indirect tax on imports/imported goods

Terms of trade (HL) an index (ratio) that shows the value of a country’s average export prices relative to their average import prices. It shows the volume of imports attainable by a country by a unit (quantity) of its exports OR the rate at which exports of a country are exchanged for imports. Formula is index of export prices/index of import prices x 100.

The law of supply states that as the price of a good rises, the quantity supplied increases, ceteris paribus

Tradeable permits are permits to pollute, issued by a governing body, which sets a maximum amount of pollution allowable. Firms may trade these permits for money.

Transfer payments are a payment received for which no good or service is exchanged, or a payment made by the government to individuals (for the purpose of redistributing income), or a form of aid where money is transferred from one country to another. e.g. a student grant or a pension.