An attribute describes information about an entity that must be captured. Each entity has zero or more attributes that describe it, and each attribute describes exactly one entity.
Each entity instance has exactly one value—possibly NULL—for each of its attributes. An attribute value can be a numeric, a character string, a date, a time or some other basic data value.
By common entity naming conventions, an entity name must be singular because each entity names an instance.
The entity with its attributes