Object-oriented programming (OOP) is a programming paradigm that uses “objects” – data structures consisting of data fields and methods together with their interactions – to design applications and computer programs.

Programming techniques may include features such as data abstraction, encapsulation, modularity, polymorphism, and inheritance. Many modern programming languages now support OOP.


OOP is designed to make it easier to develop large-scale applications by making the code more modular and extensible. The use of objects makes it possible to create relationships between different parts of the code, which can make the code easier to understand and maintain. OOP also makes it possible to reuse code, which can save time and money when developing new applications.

Objects are created from templates called classes, which define the objects' data fields and methods. A class is a template for creating objects. A class defines the object’s data fields and methods.


Inheritance is a powerful tool, but it can lead to problems. For example, if two classes inherit from a common superclass, any changes to the superclass will affect both subclasses. This can make code difficult to maintain and debug.

In addition, inheritance can make code difficult to understand. A subclass inherits all the methods and variables of its superclass, even if those methods and variables are not used by the subclass. This can make it hard to figure out what a particular class does.

Real-world examples

OOP can be used to structure software in a way that mirrors real-world relationships. For example, an object representing a person might contain data fields for name, age, address, and so on, as well as methods like walk() or talk().

OOP is often used to develop software that models complex systems. For example, a model of an ecosystem might include objects representing different species of animals, plants, and microorganisms, as well as the physical environment like land, water, and air. These objects would interact with each other in realistic ways (e.g., a plant object might take in carbon dioxide from the air object and produce oxygen that is released into the air object).

Polymorphism and encapsulation

OOP languages typically provide features like polymorphism, which allows objects to behave differently in different contexts; and encapsulation, which hides an object’s internal details from other code.

In the Java programming language, for example, objects can be created from any class and can be assigned to variables of any compatible type. A variable of a given type can refer to an object of any subclass of that type. This flexibility allows code to be written in a more general way, which is easier to maintain and reuse.

When an object is created, its initial state is determined by the values assigned to its instance variables. An object’s behavior is determined by the methods that operate on it. In OOP languages, methods are associated with classes and are inherited by subclasses. This means that a subclass can inherit the behavior of its superclass and can add new behavior of its own.

OOP can make code easier to understand and maintain by making its structure more apparent. It can also make code more flexible, since objects can be easily reused in different contexts. OOP is often used in game development, as it can help to model real-world objects and interactions. It can also make code more modular, making it easier to add new features or fix bugs.

In general, OOP is considered to be a good programming practice, since it can help promote code reusability, flexibility, and maintainability.