Cashback is a type of reward or incentive system usually offered to customers for purchases or various transactions. Cashback means that a part of the expenses is paid back to the customer, usually a certain percentage. This system can be implemented in various ways:

1. Credit Cards: Some credit cards offer a certain percentage cashback on purchases. This usually takes the form of a portion of the money spent being returned to the cardholder's account.
2. Loyalty Programs: Retail stores or online shopping sites can run loyalty programs by offering their customers cashback at certain rates on their purchases.
3. Bank Promotions: Some banks may offer cashback offers for certain accounts or financial products. This usually applies to transactions made under certain conditions.

The purpose of cashback offers is usually to increase customer loyalty and generate more sales or to promote certain financial products. For customers, these offers offer the opportunity to save money on their purchases.