A payment gateway processes the payment requests submitted on your behalf by Chargify as specified for each of your customer subscriptions. The payment gateway notifies Chargify if each charge is approved or denied. If approved, the settlement process begins via the payment gateway which results in the funds being deposited into your merchant account.
To configure, refer to the section, Payment Gateway.
You can find a complete list of the payment gateways which work with Chargify here: payment gateway list.