What are the Revenues incurred by the bank through credit cards issued to its customers ?

Offsetting the costs are the following revenues:

Interchange fee
Main article: Interchange fee
In addition to fees paid by the card holder, merchants must also pay interchange fees to the card-issuing bank and the card association. For a typical credit card issuer, interchange fee revenues may represent about a quarter of total revenues.

These fees are typically from 1 to 6 percent of each sale, but will vary not only from merchant to merchant (large merchants can negotiate lower rates), but also from card to card, with business cards and rewards cards generally costing the merchants more to process. The interchange fee that applies to a particular transaction is also affected by many other variables including: the type of merchant, the merchant's total card sales volume, the merchant's average transaction amount, whether the cards were physically present, how the information required for the transaction was received, the specific type of card, when the transaction was settled, and the authorized and settled transaction amounts. In some cases, merchants add a surcharge to the credit cards to cover the interchange fee, encouraging their customers to instead use cash, debit cards, or even cheques.

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Interest on outstanding balances
Interest charges vary widely from card issuer to card issuer. Often, there are "teaser" rates in effect for initial periods of time (as low as zero percent for, say, six months), whereas regular rates can be as high as 40 percent. In the U.S. there is no federal limit on the interest or late fees credit card issuers can charge; the interest rates are set by the states, with some states such as South Dakota, having no ceiling on interest rates and fees, inviting some banks to establish their credit card operations there. Other states, for example Delaware, have very weak usury laws. The teaser rate no longer applies if the customer does not pay their bills on time, and is replaced by a penalty interest rate (for example, 23.99%) that applies retroactively.

Fees charged to customers
The major fees are for:

• Late or overdue payments
• Charges that result in exceeding the credit limit on the card (whether deliberately or by mistake), called overlimit fees
• Returned cheque fees or payment processing fees (e.g. phone payment fee)
• Cash advances and convenience cheques (often 3% of the amount)
• Transactions in a foreign currency (as much as 3% of the amount). A few financial institutions do not charge a fee for this.
• Membership fees (annual or monthly), sometimes a percentage of the credit limit.
• Exchange rate loading fees (sometimes these might not be reported on the customer's statement, even when applied). The variation of exchange rates applied by different credit cards can be very substantial, as much as 10% according to a Lonely Planet report in 2009.
• In the U.S., the Credit CARD Act of 2009 specifies that credit card companies must send cardholders a notice 45 days before they can increase or change certain fees. This includes annual fees, cash advance fees, and late fees. 

Courtesy: Wikipedia