A transaction performed by using a payment card to determine if the card holder has sufficient funds on his/her card to pay for a given transaction. An authorization will take only seconds, and allows the merchant to ensure that payment will be taken from the card.
When an authorization is declined, there are a few possible outcomes. If the customer has insufficient funds in his account, the card will be declined and returned to the customer; if the card has been stolen or canceled then the merchant will cut the card in two. When an unauthorized card is used for an online transaction, the transaction will simply be declined.