E-R Model:

An Entity Relationship model was introduced by P. P. Chen in 1976. An E-R Model is defined as a Conceptual Data Model that views the real world as Entities and Relationships. An E-R Model is useful to a database designer in following ways:

1. An E-R Model maps well to the relational model i.e., the constructs used in the E-R Model can be easily transformed into Relational Tables.
2. An E-R Model can be used by the database designer to communicate the design to the End Users.
3. An E-R Model can be used as a design plan by the Database Developer to implement a Data Model in specific DBMS Software.