The Merchant of Record (MoR) is a term specific to the processing of credit/debit card payments. The MoR is the company who collects payments directly from a customer in exchange for providing services (e.g. finding the right flight or travel package). The name of the merchant of record appears on the customer's credit or debit card statement.
When a customer books a flight from you, being the MoR means you're taking on the responsibility for providing the customer assistance from adding bags to a flight to arranging alternative flights if their intended journey is cancelled. When you also use Managed Content to book flights Duffel helps make this as easy and painless as possible to provide your customers with a great post-booking experience.
Being the MoR means you are also liable for any fraudulent transactions, chargebacks or refunds in the event of airline insolvency.