Entity Instance

Entity instance is a single occurrence of an entity type. In other words, you can say that a member of an entity class is called entity instance. An entity type is described just once in a database, while many instance of an entity type has its own values.

The basic object that the E-R Model represents is an entity, which is “a thing’’ in real world with an independent existence which is the most important item in the data file of E-R Model. You can also say that anything in a real world that has a set of different attributes or properties is known as entity. An entity can be an object with a physical existence such as person, place, car, computer, house, student and a teacher.

Each entity type is given a unique name. In E-R diagram a rectangular box is used to represent the entity.