There are six different transaction types that can be submitted to the Authorize.Net Payment Gateway but NopCommerce uses only two of them as follows:

1. Authorize (AUTH_ONLY)

You request an authorization when a customer makes a purchase. An authorization, provided by the customer’s card issuing bank, confirms the cardholder’s ability to pay, ensuring that the customer's credit card account is in good standing with sufficient funds to complete the purchase.

An authorization ensures that your customer's credit account is open, in good standing, and has sufficient funds to complete the submitted transaction.  If the card passes these checks, the issuing bank will place a hold on the funds for the amount of the authorization.

When an AUTH_ONLY transaction is submitted to Authorize.Net, we send the transaction to your processor for authorization. If approved, the transaction is placed in your Unsettled Transactions with a status of Authorized/Pending Capture. The authorization places the funds on hold with the customer's bank. When the transaction is captured, the funds transfer process will occur. This can be useful in situations where you need to make a sale, but won't be able to ship merchandise for several days. You can authorize the transaction to ensure funds availability, then capture the transaction to obtain the funds upon shipment. AUTH_ONLY transactions are only kept in your Unsettled Transactions for 30 days. If an AUTH_ONLY transaction is not captured for settlement within 30 days, the transaction status will change to Expired, and the funds will not be transferred. To capture a transaction, you can manually log into your Authorize.Net interface and go to your Unsettled Transactions. From there, you can use the Group Capture filter toward to the top of your screen to capture multiple transactions at once, or click the individual Transaction ID of the transaction you would like to capture, and the next screen will provide a Capture button.

2. Authorize and Capture (AUTH_CAPTURE)

For a transaction to be completed successfully, you need to perform an authorization and a capture on the transaction.

An authorization ensures that your customer's credit account is open, in good standing, and has sufficient funds to complete the submitted transaction.

If the card passes these checks, the issuing bank will place a hold on the funds for the amount of the authorization.

After a successful authorization has been completed, you will need to perform a capture to transfer funds from the customer's bank account to your merchant bank account.

This is the default transaction type. When using AIM, if the x_type field is not sent to us, the type will default to AUTH_CAPTURE. Simple Checkout uses AUTH_CAPTURE only. The Virtual Terminal defaults to AUTH_CAPTURE unless you select a different transaction type.

With an AUTH_CAPTURE transaction, the process is completely automatic. The transaction is submitted to your processor for authorization and, if approved, is placed in your Unsettled Transactions with the status Captured Pending Settlement. The transaction will settle at your next batch. Settlement occurs every 24 hours, within 24 hours of your Transaction Cut-off Time.