Shopp integrates with lots of payment processing services, known as payment gateways.
Payment gateways are essentially the online equivalent of a credit card terminal. To accept a payment, your shopping cart software must integrate with your payment gateway. Shopp integrates with about 20 different payment gateways. Included with the core plugin are the following 4 payment gateways: PayPal Standard, PayPal Express, 2Checkout and Google Checkout. There are also 2 payment systems included in the core plugin that do not communicate with any service providers: Offline Payments and the Test Mode system. The rest of the payment gateways for Shopp are available as add-ons that you can buy individually at the Shopp Store.