Entity is an object that exists in the system, modeled and represented by its state, interactions, and relationships with other entities. In computing, entity is often used to refer to a particular application object like a user, or a technical object like a file. Entities comprise the data that is stored and managed in a relational database, and objects that are created, modified, or deleted as part of the application’s processing and data management activities.
In object-oriented programming, entity is used to represent a particular real-world thing, such as a person, book, user, or post. An entity object encapsulates information and behaviors like properties, methods, events, and other related objects. The relationship between the entity object and the data stored in a database is typically represented by a database-agnostic object-relational mapping (ORM) system or layer.
Entities can be related to other entities, often by means of relationships. These relationships further define how the entity behaves and provide more information about the object. These relationships can be direct, like a person’s address, or they can be indirect, like a person’s relationships to friends, family, or other people. Relationships between entities can be of various types, like a one-to-one, one-to-many, or many-to-many.
In some cases, relationships can also represent hierarchies between objects. For example, an employee can be related to their manager, and the manager in turn can be related to their superiors. This establishes a chain of associations between objects and allows the software to make queries and determine the correct behavior and data of an object.
Entity has become an important component in many programming frameworks and paradigm that involve building distributed applications, such as distributed entity models, and object-graph-oriented architectures. Entity is also used in business process models, application development, and software engineering.
