When you swipe your credit card, the information on the magnetic stripe on the back of the card is read by a card reader. This information includes the card number, the expiration date, and the cardholder's name. The reader then sends this information to the merchant's bank or payment processor, which checks the card number against a database of valid card numbers and verifies that the card is not on a list of stolen or lost cards. If the card is valid, the payment processor sends an authorization request to the cardholder's bank for the amount of the transaction. The cardholder's bank then checks the account to ensure that there are sufficient funds to cover the transaction and sends an authorization code back to the payment processor. Once the payment processor receives the authorization code, it sends the code back to the merchant's bank, which in turn sends the code back to the card reader. The card reader then prints out a receipt for the customer to sign, and the transaction is complete. Overall, the process of swiping a credit card involves several steps of verification and authorization to ensure that the transaction is legitimate and that the cardholder has sufficient funds to cover the purchase.