Payment Gateway is a service that is used to process online payment transaction when accepting online orders from your customers. Payment Gateway is an interface from the internet to the payments computer network of the respective credit card organization. Payment Gateways are offered by different banks and other dedicated Payment Processors. A payment gateway is a service provided by a billing processor, which allows credit card information to be collected and passed over the internet. A Payment Gateway can be thought of as a digital equivalent to a credit card processing terminal. Although there are many payment gateways available, some of the most popular include Paypal, AuthorizeNet, USAePay and Verisign. A software usually provided by a third party such as Authorize.Net that allows a website to be integrated to a merchant account. Most major merchant account providers include a gateway with their services. Allows the secure transfer of credit card funds from users on your website to your merchant account. The requirements for an account vary from service to service, with specific requirements described on the web sites of most gateway providers.