Once an order has been placed, the funds allocated for that purchase will be temporarily on hold -- this is the standard pre-authorization period. While this is not an official charge, it is a step towards ensuring there are sufficient funds in the account to successfully complete the transaction.
The amount owed will only be officially deducted from your account once the order has been approved. At that point, the order will be prepared for shipment and the initial pre-authorization charge will automatically be voided.
Cancelling an order will result in the immediate voiding of the transaction. Please note that it may take your bank additional time to allocate the funds back into the account and update your statement.