Glossary
What is a promotion?
A promotion is a rule that fires automatically at scan time, such as double stamps on a quiet weekday. Nobody buys a promotion. It is configured by the business, evaluated when a customer is scanned, and it may result in extra stamps or in a voucher being issued.
A promotion is the only one of the three that a customer never chooses. It is a rule sitting in the background, evaluated at the moment of a scan.
What promotions are good for
Promotions move behaviour you can name: a slow trading hour, a product you are trying to introduce, a month where regulars usually drift. They also fire without the customer choosing them. That makes them the easiest way to spend more than you meant to, so put an end date on them.