The stamp system is the one where customers receive stamps for the products they buy or the services they opt for, irrespective of the amount spent. For example, a coffee stamp or hair cut stamp or a car wash stamp.
Generally, for this kind of system rewards and redeem the offer is already defined at the time of giving a stamp so customers already know what to expect if they collect a certain number of stamps. This is an easy way for customers to know offers and an easy way for businesses to set up offers.
This kind of system is generally used by business that has a small list of products to sell or a small list of services to offer like coffee cafe, hairdresser, fitness centre, beauty salon, restaurants, car wash, etc.