What must happen in order for exchange to occur?

For exchange to occur, there must be at least two parties involved, each possessing something of value that the other desires. Both parties must also agree on the terms of the exchange, which includes the value of the items or services being traded. Additionally, there needs to be a mechanism for the transaction to take place, whether it be a marketplace, legal framework, or informal agreement. Finally, mutual consent and trust between the parties are essential to facilitate the exchange.