Data model perspectives

Data model perspectives are defined by ANSI as follows:

• Conceptual data model: Describes the domain semantics, and is used to communicate the main business rules, actors, and concepts. It describes the business requirements at a high level and is often called a high-level data model. 
• Logical data model: Describes the semantics for a certain technology, for example, the UML class diagram for object-oriented languages.
• Physical data model: Describes how data is actually stored and manipulated at the hardware level, such as storage area network, table space, CPUs, and so on.

According to ANSI, this abstraction allows changing one part of the three perspectives without amending the other parts. One could change both the logical and the physical data models without changing the conceptual model. To explain, sorting data using bubble or quick sort is not of interest for the conceptual data model. Also, changing the structure of the relations could be transparent to the conceptual model. One could split one relation into many relations after applying normalization rules, or by using enum data types in order to model the lookup tables.