Step 1 : Introduction to the question "What are the first four digits of all Discover Card numbers?"
No matter what credit card you carry in your wallet, it shares some physical characteristics with the cards used by consumers across the U.S. The first six digits of each credit card number make up the issuer identifier, which denotes the credit card network to which the number belongs. For Discover cards these digits must be "6011-xx". The Discover Card was introduced by Sears in 1985. At the time Discover was introduced, Sears was the largest retailer in the United States. Discover is the fourth largest credit card brand in the U.S., behind Visa, MasterCard and American Express, with nearly 44 million cardholders.
