Specialisation means concentrating on producing a narrow range of goods, services or tasks instead of trying to produce everything. Exchange means trading what has been produced for goods or services made by someone else.

For example, Worker A specialises in plumbing services and Worker B specialises in accounting services. Worker A provides plumbing services to Worker B, while Worker B provides accounting services to Worker A. The money payments flow in the opposite directions: Worker B pays Worker A for the plumbing services, and Worker A pays Worker B for the accounting services.