System designers use models to represent their understanding of a system as well as the way it can be implemented. Different considerations apply when conceptualising the function of a system, defining its organisation or specifying how it should be constructed. In the past the translation, or mapping, between these different models was largely improvised, based on the experience and genius (or lack of such) of the designers. All too often considerations of one domain intruded on the activities of another, causing confusion at best. One of the main aims of the Model-Driven Architecture (MDA) is to clearly identify and separate these domains while providing the right kind of bridges between them.
In MDA, the system concept is elaborated in a Computation-independent Model (CIM) which relates to the role played in the business by the intended system. MDA defines system functionality using a platform-independent model (PIM). The PIM is translated to one or more platform-specific models (PSMs) that computers can run.