When you checkout, an order form is displayed where you can fill out your contact and payment information. If you specified to ask for returning customers during First Time Setup, the script will first ask the customer if they've purchased before, and for their Customer ID#. If they enter a valid customer ID#, they will be prompted to confirm the information, then brought to the order form. This way, the customer does not have to enter their contact information again, and instead, only has to enter their payment information.

Once an order is submitted, the shopping cart will first determine the total amount to charge the customer. First, all products in the customer's cart are added up. Next, all taxes are checked, and if any match the customer, they will be added to the total amount. Last, the shopping cart checks for a coupon code, and if needed, subtracts the needed amount.

The payment is then physically processed. If the customer is paying through a third party payment processor, such as PayPal or 2CheckOut, the order will be added to the database with the status of pending, and the customer will be automatically redirected to the needed payment server. Once the customer has submitted payment, the third party payment processor will contact the shopping cart on your server. The shopping cart will then automatically approve the order, without any intervention from you.

Otherwise, if you have a real merchant account, and accept credit cards on your server, the credit card will be authorized / charged behind the scenes, in real time. If declined, the customer will receive an error saying their credit card has been declined. If approved, the order will be added to the database with a status of either approved or pending, depending on your settings.