Differential object marking is a marking of the object of the verb which depends on properties of the nominal component constituting the object or of its referent.

Factors determing differential object marking properly include definiteness (definite -> marked, indefinite -> unmarked) and empathy of the object (empathic -> marked, anempathic -> unmarked).

Example: In Spanish, the direct object is marked by the preposition a if it is human and specific.