Credit Card Hidden Information

We use credit/debit card in our daily life. Number printed on our card play a significant role in our transaction but those numbers are not only use for making transaction but also have some hidden information which is helpful to identify if our card is valid or not. I came to know about such information.

Numbers on our card is allocated in accordance with ISO/IEC 7812

1. The first digit of a credit card number is Major Industry Identifier. It identifies the industry within which the card is primarily to be used.

MII digit	Issuer category
0	ISO/TC 68 and other industry assignments
1	Airlines
2	Airlines and other future industry assignments
3	Travel and entertainment and banking/financial
4	Banking and financial
5	Banking and financial
6	Merchandising and banking/financial
7	Petroleum and other future industry assignments
8	Healthcare, telecommunications and other future industry assignments
9	For assignment by national standards bodies

2.  Issuer identification number (IIN)
The first 6 digits are the Issuer Identification Number also called as "bank identification number" (BIN). It will identify the institution that issued the card. Below are few IINs

Issuing network	IIN ranges	Length	Validation
American Express	34, 37	15	Luhn algorithm
Bankcard	5610, 560221-560225	16	Luhn algorithm
China UnionPay	62	16-19	no validation
Diners Club International	300-305, 309, 36, 38-39	14	Luhn algorithm
Discover Card	6011, 622126-622925, 644-649, 65	16	Luhn algorithm
Maestro	5018, 5020, 5038, 5612, 5893, 6304, 6759, 6761, 6762, 6763, 0604, 6390	12-19	Luhn algorithm
MasterCard	51-55	16	Luhn algorithm
Visa	4	13, 16	Luhn algorithm
Visa Electron	4026, 417500, 4405, 4508, 4844, 4913, 4917	16	Luhn algorithm

 3. Account Number
Take out first 6 and last digit and remaining digit represents account number

4. Check Digit 
last digit in number is considered as Check digit used to validate credit card number. 

refer : http://www.codeproject.com/Tips/515367/Validate-credit-card-number-with-Mod-algorithm , 

http://money.howstuffworks.com/personal-finance/debt-management/credit-card1.htm