Imprint is a CAD preparation feature, which helps the recognition of interfaces. The interfaces will later on be assigned as contacts in Conjugate Heat Transfer (CHT) or structural analysis. Definition of contacts is important because these regions are responsible of transferring heat and loads.
The following picture represents an assembly, which consists of two solid parts and an air domain. Without imprint operation, the interface between the solid bodies won’t be correctly recognized and will be grouped as partial interface. The highlighted face (blue) shares contact with both an air domain and a solid body. The face should be split into two interfaces, one between the solid part, and the other between the air domain.
Using imprint feature, interfaces between parts are separated. Now, the contacts are recognized correctly: