PIN or the Personal Identification Number is unique to every card and is a combination of numbers. It is normally a 16 digit number with the first 8 digits reserving information about the card issuer and the country. The next 8 stores customer information like the category of the member ( whether is a businessman, individual or NRI ). The PIN serves as a key, which allows you to avail certain services like cash withdrawal from automatic teller machines. This number is very important and must be stored carefully. Most credit card issuing banks instruct their clients to write the PIN in a very safe place or better still, to simply memorize the digits.