Card pre-authorization is commonly referred to as pre-auth. You can think of it as a pre-approval process to ensure that the customer is using a valid credit card.

Charges can get declined for multiple reasons.

When the cardholder receives their card statement at the end of the billing cycle, your statement name will appear as `OPN*XXXXXX` where the XXXXXX is your unique identifier (merchant).

Recurring billing (also known as subscription payments) can be achieved easily using the [Schedule API](https://www.omise.co/charge-schedules-api), or manually setting up a charge schedule on the dashboard.