The INTERNET Gateway is a secure web server that provides an interface for merchant websites that require real-time transaction processing.
The merchants either have an SSL server or not and can connect via http with the payment gateway to get a real-time credit card authorization.
The fastest-growing segment of credit card use today is in “card-not-present" transactions in which a customer makes his or her purchase by mail order or telephone order (MOTO), by facsimile, or via the Internet instead of being physically present at the merchant's location.
If you want to process credit cards for Internet, telephone, or mail order transactions, you'll need a special merchant account specifically designed for that purpose.
Because you never take physical possession of a credit card so that you can swipe it through a magnetic strip reader, both Visa and MasterCard use different criteria for evaluating risk and have different fee structures for card-not-present transactions.