A pending invoice is an invoice that has not been approved or discarded and will not be collected on until it is approved.
For example, you can generate a pending invoice during the account registration process to verify that sufficient funds are available on a customer’s credit card before attempting a collection (this verification is also referred to as a "credit card authorization"). After the authorization has been successfully completed, the pending invoice can be approved and a collection can be attempted.
If you have pending invoices enabled in your Aria implementation, you can review them for accuracy before approving them. After approving the invoices, Aria will collect payments from customers for whom the invoices were generated. You also have the option to re-calculate inaccurate invoices, then approve the re-generated invoices. In addition, you can discard unnecessary invoices and, optionally, cancel any orders associated with those invoices.