Wikipedia
Cashier-as-a-Service
Cashier-as-a-Service (CaaS) refers to using a third party service as payment. When a shopper buys merchandise online, oftentimes, the shopper does not pay the merchant directly, but rather through a third party - the cashier. The cashier is trusted by both the shopper and the merchant and is expected to allow for reliable and secure transfer of money. By paying a merchant through a cashier, shoppers are able to pay for merchandise without giving away their financial information to the merchants.