What term describes the act of selling or buying something?

The term "transaction" specifically refers to the act of selling or buying something and denotes a single instance of such an agreement or exchange. In a transaction, there is typically a transfer of goods or services for payment, which embodies the core concept of trade between two parties. Each transaction is a distinct event that can involve various details like pricing, terms, and the nature of the goods or services exchanged.

While "trade" and "exchange" may also describe similar activities, they have broader or slightly different meanings. Trade encompasses larger activities related to the buying and selling of goods on a grander scale, often including ongoing relationships between parties. Similarly, exchange can refer to the act of giving one thing and receiving another, which may not always involve a monetary transaction. "Commerce" involves the overall system of buying and selling on a larger scale, often intertwined with economic policies and market dynamics. Hence, "transaction" is the most precise term for defining the act of selling or buying something.