The Merchant Discount Rate (MDR) is a fee that merchants pay to accept card payments from customers. This fee is typically a percentage of the transaction amount and is charged by the payment processor or bank that facilitates the card transaction. The MDR covers various costs, including transaction processing, fraud protection, and other services provided to the merchant. MDR can vary based on several factors, such as the type of card used (credit or debit), the merchant's industry, and the volume of transactions processed. Understanding the MDR is essential for merchants to manage their payment processing costs effectively and maximize their profits.