Object (computer science)

In software development, an object is an entity that has state, behavior, and identity. An object can model some part of reality or can be an invention of the design process whose collaborations with other such objects serve as the mechanisms that provide some higher-level behavior. Put another way, an object represents an individual, identifiable item, unit, or entity, either real or abstract, with a well-defined role in the problem domain.

A programming language can be classified based on its support for objects. A language that provides an encapsulation construct for state, behavior, and identity is classified as object-based. If the language also provides polymorphism and inheritance it is classified as object-oriented. A language that supports creating an object from a class is classified as class-based. A language that supports object creation via a template object is classified as prototype-based.

The concept of object is used in many different software contexts, including:

• Possibly the most common use is in-memory objects in a computer program written in an object-based language.

• Information systems can be modeled with objects representing their components and interfaces.

• In the relational model of database management, aspects such as table and column may act as objects.

• Objects of a distributed computing system tend to be larger grained, longer lasting, and more service-oriented than programming objects.

• Actor model – Model of concurrent computation
• Business object – Entity within a multi-tiered software application
• Instance (computer science) – Concrete manifestation of an object (class) in software development
• Object lifetime – Time period between the creation and destruction of an object-oriented programming instance
• Object copying – Technique in object-oriented programming
• Semantic Web – Extension of the Web to facilitate data exchange

• What Is an Object? from The Java Tutorials