High school politics, why barter is accidental, how to understand it, can you set up a stall?

Accidental barter: refers to the initial commodity exchange of human beings at the end of primitive society, which occurred under the extremely accidental situation that both tribes had surplus products. The exchange of goods at this time is very accidental, so it is called accidental barter.

Expand barter: With the development of productivity and social division of labor, the frequency of barter is frequent, and the types of goods involved in the exchange are also increasing. At this time, commodity exchange is an expanded barter exchange.

There is also a difference between the stalls you mentioned. For example, in the current form of stalls, stall owners pay for goods, and all they need is money. Consumers do not need specific goods to exchange, thus meeting the needs of both parties. In primitive society, the monetary system was not perfect, and only barter was available. This condition that the needs of both parties are met is much lower in probability, so most of them are accidental things, so there is a demand for barter.