What is a payment gateway and what does it do?
The payment gateway is the agency responsible for verifying credit card information and affirming that there are sufficient funds to cover a purchase. Examples of these are Authorize.net, Verisign, and Linkpoint API (from Cardservice International). These companies pass the information to their merchant bank that in turn contacts the credit card issuer, which approves or denies credit. Notice of approval or denial is then forwarded back down the chain to the merchant. You must have a payment gateway attached to your account to do real-time credit card processing over the Internet.
