An enterprise knows certain characteristics about each of the entities with which it deals. Typically, analysts know the same kinds of characteristics about each entity belonging to the same entity type.
For example, CUSTOMER characteristics that are of interest to the business are:
Each of these possible characteristics of entities of the entity type CUSTOMER is named an attribute. An attribute is a descriptor whose values are associated with individual entities of a specific entity type.
A set of attributes describes each entity type. An attribute can belong only to an entity type. It cannot therefore describe a relationship and must not have attributes of its own.
Each entity has one attribute value for each of its attributes. An attribute value is a descriptor whose values are associated with individual entities of a specific entity type.
For example, one entity of the entity type CUSTOMER has James Molt as an attribute value for its Name attribute.
The multi-valued attributes can be modeled.
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