The domain model identifies and describes the flow of information, data structures, constraints and controls, within a problem domain.
Definition from Patterns of Enterprise Application Architecture :
“an object model of the domain that incorporates both behaviour and data.”
Objects should provide a meaningful and logical representation of an individual part of a system and its relationships to other parts of the system. Domain modelling is part of the Analysis phase of software development.
Generation of object models, data schemas. see Domain Logic.