An entity-relationship model describes the relevant data objects, their attributes, and their relationships within a system or domain.
Entity types represent important concepts, such as Customer or Order. Attributes describe their properties. For example, a Customer may have a name and a unique customer number.
Relationships connect entity types. Moreover, cardinalities define how many instances may participate. For example, one customer may place several orders.
Teams often present the model as an entity-relationship diagram. However, textual rules can provide additional details and constraints.
This model focuses on static data structures. Therefore, it does not describe processes, interactions, or system behavior. Teams use other models for these aspects.
At the conceptual level, the model avoids technical database details. Later, designers can transform it into tables, columns, keys, and relationships.
Clear entity-relationship models support data requirements, shared terminology, database design, and system validation.
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