sentences:  Within the field of software engineering both a data model and an information model can be abstract, formal representations of entity types that includes their properties, relationships and the operations that can be performed on them.The entity types in the model may be kinds of real-world objects, such as devices in a network, or they may themselves be abstract, such as for the entities used in a billing system.Typically, they are used to model a constrained domain that can be described by a closed set of entity types, properties, relationships and operations.