A cash advance is a service provided by most credit card and charge card issuers. The service allows cardholders to withdraw cash, either through an ATM or over the counter at a bank or other financial agency, up to a certain limit. For a credit card, this will be the credit limit (or some percentage of it).
Cash advances, these will be processed as regular credit card transactions. Many merchants have passed on the credit card processing fees to the credit card holders in spite of the credit card network's guidelines, which state the credit card holders should not have any extra fee for doing a transaction with a credit card.
Under card scheme rules, a credit card holder presenting an accepted form of identification must be issued a cash advance over the counter at any bank which issues that type of credit card, even if the cardholder cannot give his or her PIN.