A conceptual model describes the data in its structure and conditions in a system
manner, based on a concept and its semantic of the real world.
To develop a conceptual model is the first step of data modelling: to define which
part of the real
world that should be modelled and for witch purpose. It is the identification of the semantics and
properties of the real world objects and their conditions and behaviour.
To describe a data model, it needs a modelling language which can be grafical (e.g. UML) or
textual (e.g. GML, INTERLIS).