Benefits to merchants

For merchants, a credit card transaction is often more secure than other forms of payment, such as checks, because the issuing bank commits to pay the merchant the moment the transaction is authorized, regardless of whether the consumer defaults on the credit card payment (except for legitimate disputes, which are discussed below, and can result in charges back to the merchant). In most cases, cards are even more secure than cash, because they discourage theft by the merchant's employees and reduce the amount of cash on the premises. Prior to credit cards, each merchant had to evaluate each customer's credit history before extending credit. That task is now performed by the banks which assume the credit risk.
For each purchase, the bank charges the merchant a commission (discount fee) for this service and there may be a certain delay before the agreed payment is received by the merchant. The commission is often a percentage of the transaction amount, plus a fixed fee. In addition, a merchant may be penalized or have their ability to receive payment using that credit card restricted if there are too many cancellations or reversals of charges as a result of disputes. Some small merchants require credit purchases to have a minimum amount (usually between $5 and $10) to compensate for the transaction costs, though this is not always allowed by the credit card consortium.
In some countries, for example the Nordic countries, banks guarantee payment on stolen cards only if an ID card is checked and the ID card number/civic registration number is written down on the receipt together with the signature. In these countries merchants therefore usually ask for ID. Non-Nordic citizens, who are unlikely to possess a Nordic ID card or driving license, will instead have to show their passport, and the passport number will be written down on the receipt, sometimes together with other information. Some shops use the card's PIN for identification, and in that case showing an ID card is not necessary.

article by : http://wikipedia.com