Attributes that are directly kept in the data base.
For example, 'Birth date' attribute of a person.
Attributes that are not stored directly but can be derived from stored attributes are known as derived attributes. For instance, The years of services of a 'person' entity can be determined from the present date and the date of joining of the person. Likewise, total salary of a 'person' can be calculated from 'basic salary' attribute of a 'person'.