First of all understanding of credit card as phenomena.
For example white guy is walking across Harlem without money, get in fast to the nearest bank. Has communicated to the manager, has signed that was given to sign and he already can spend $3000 as soon as will receive a card, and becomes a cardholder. It’s called Credit line - the amount of the credit which the bank lets to spend.
Has come through road in weapon, has bought on a card a colt and at it has increased
Current Balance - how much was spent, so much then needed to return to bank. It’s subtracted from credit line.
Available Credit - how much money is available for spending.
The card or the credit usually is given for year or some years. Therefore there is expiration date is written on the card.
Expiration date - month and year of ending a contract with a bank. For example 10/2009.
Each card is unique on a planet. For this reason it has:
Card Number - number, usualy 16-digit. Rarely you can see 13-digit. In American Express by default 15 digits.
Watch and take care of all this large object of calculations on credit cards Visa and Mastercard/Eurocard - international payment systems. In Visa number of a card begins from 4, at Masterkard - 5. Other brands not so are developed (American Express, Discover, JCB, the Gold Crown, etc.)
