Why you might need a credit card payment gateway:
Almost all successful ecommerce sites have credit card payment
gateways, allowing the customer to pay instantly* with their cards
(in minutes) so that the merchant can start shipping the product
immediately. This is good for both, the merchant and the customer.
* If you accept only check payments from customers,
you have to wait until you receive the check, and then further
wait until the check clears, before you ship him the product.
