MFN means most-favored-nation which is a tariff treatment. It is bilaterally given and provides for the lowest tariff in the tariff code. It is important to understand that the term most-favored-nation gives the impression that the tariffs involved are the lowest, it is in fact not the cast. MFN is not really special but is just normal trading status. GSP(generalized system of preferences) establishes even lower tariffs than MFN.