A credit card number is the long set of digits displayed across the front or back of your plastic card. It is typically 16 digits in length, often appearing in sets of four. Sometimes it can be as long as 19 digits, and it is used to identify both the credit card issuer and the account holder.
Credit card numbers are not randomly assigned. They’re coded so that they identify the issuer, to help prevent identity thieves from simply guessing at account numbers and committing fraud. The credit card number must fit a complex pattern in order to work.
Most of us carry credit cards and ATM cards. These, typically, have sixteen digits on the front. These digits are the unique account number for the card. For obvious reasons, just any sixteen digits will not work, they follow pattern.
If want more, information
You card number is the long number on your credit card (around 19 digits)
If what you are asking is the small CVV or CID number:
For Visa®, Mastercard®, and Discover® cardholders:
Turn your card over and look at the signature box. You should see either the entire 16-digit credit card number or
just the last four digits followed by a special 3-digit code. This 3-digit code is your CVV number / Card Security Code.
American Express® cardholders:
Look for the 4-digit code printed on the front of your card just above and to the right of your main credit card number. This 4-digit code is your Card Identification Number (CID). The CID is the four-digit code printed just above the Account Number.