A customer loyalty program is a rewards program that a company offers customers to encourage them to continue to shop with them.
Traditionally, loyalty programs involved the business issuing the customer a loyalty card (variously called a rewards card or advantage card) which was visually similar to a credit card. The customer would swipe this card at every purchase and then get discounts on their current purchase or points toward a future purchase.
More recently, companies have been using mobile online loyalty programs. Instead of swiping a loyalty card at checkout, the customer opens an app and shows a QR code that gets scanned at the register. The scanning process has moved from cards to phones but the rewards part has mostly remained the same.