This data model is based on real world that consists of basic objects named entities and of relationship among these objects. Entities are illustrated in a database by a set of attributes. An Entity - Relationship model is an abstract way to define a database. It generally starts with a relational database, which loads data in tables. Some of the data in these tables point to data in other tables - for instance, your entry in the database would point to various entries for each of the phone numbers that are yours. The ER model would define that you are an entity, and each phone number is an entity, and the relationship between the phone numbers and you is 'has a phone number'. Diagrams prepared to design these relationships and entities are called E-R diagrams or entity-relationship diagrams.