Pillars of Object Oriented Programming A Beginners Guide

Pillars of Object Oriented Programming: A Beginner’s Guide

The Pillars of Object-Oriented Programming: A Beginner’s Guide


Object-Oriented Programming, or OOP for short, is a programming model based on the concept of objects. OOP allows developers to create reusable and modular code. In the OOP model, objects interact with each other to create complex systems. The pillars of OOP are the fundamental concepts that make this programming paradigm possible. To master OOP, one needs a good understanding of these pillars. In this article, we will explore the four pillars of OOP, namely Encapsulation, Inheritance, Abstraction, and Polymorphism.


Encapsulation is the first pillar of OOP, and it refers to the practice of hiding data and methods within an object. This makes the object’s internal workings less exposed, which makes it easier to maintain and update. Encapsulation involves the use of access modifiers to control access to an object’s properties and methods. Good encapsulation ensures that objects are independent, so any changes made to one object don’t affect others that interact with it.


Inheritance is the process of basing a new class on an existing class. The resulting subclass inherits all the properties and methods of the parent class. The advantage of inheritance is that it promotes code reuse and reduces redundancy. It is ideal when you want to create similar objects with slight variations. Inheritance also facilitates customization of properties and methods of parent classes to suit specific needs.


Abstraction is the third pillar of OOP, and it refers to the process of simplifying complex systems by identifying and focusing on essential features. In the OOP model, abstraction involves creating abstract classes and interfaces that define general properties and methods, which other classes can inherit. Abstraction allows developers to focus on what objects do, rather than how they do it. It also promotes code reuse, as abstract classes can be used to create multiple similar objects.


Polymorphism is the fourth pillar of OOP, and it refers to the ability of different objects to respond to the same message or method call. Polymorphism allows developers to write code that works with different types of objects without having to know their specific type. This improves code flexibility and reusability. An example of polymorphism is the “+” operator that can add numbers, concatenate strings, or merge arrays.

In conclusion, understanding the pillars of OOP is crucial to writing clean and maintainable code. Encapsulation, inheritance, abstraction, and polymorphism are the foundational concepts of OOP that make code reuse and modularity possible. As a beginner, it is essential to master these concepts before moving on to more advanced OOP features.

What Are the Pillars of Object-Oriented Programming?

1. Encapsulation

Encapsulation is a fundamental pillar of object-oriented programming that involves the bundling of data and associated methods into a single unit called a class. Encapsulation allows for the hiding of data within a class, protecting it from external interference or modification. This promotes secure and organized code and makes it easier to refactor as changes to one part of the code won’t affect other parts.

Examples of Encapsulation include access modifiers such as private, public or protected which restricts external access to class data, and the use of getters and setters to allow controlled access to the private data within a class.

2. Inheritance

Inheritance is the process of creating new classes from existing classes by inheriting properties and methods of the parent class. When a new class is derived from a parent class, it can use any of the variables and methods from the parent class, reducing the amount of code duplication and promoting a more organized structure. Inheritance is one of the core principles of OOP that also enables code reusability.

Examples of Inheritance include the use of superclasses and subclasses, where a subclass inherits the attributes and behaviors of the superclass, overloads a method by providing a new implementation.

3. Abstraction

Abstraction refers to the process of providing only essential information to the user while hiding specific details. Through abstraction, we define the critical features of an object that are necessary for interaction and ignore the unnecessary details. Abstraction helps in reducing code complexity, promoting code reuse, and modularization. It also allows developers to focus solely on what the code should do rather than how it should do it.

Examples of Abstraction include the use of abstract classes and interfaces, where the abstract class defines properties and behaviors that are common among a number of derived classes, thus promoting code reuse.

4. Polymorphism

Polymorphism refers to the ability of an object to take on many forms. In object-oriented programming, polymorphism allows developers to use the same interface for different implementations, enabling a more modular and extensible code. Polymorphism is classified into two types, static and dynamic polymorphism

Static polymorphism refers to polymorphism that is resolved at compile-time, while dynamic polymorphism refers to polymorphism that is resolved at runtime.

Examples of Polymorphism include method overloading and method overriding, where method overloading involves defining two or more methods with the same name in the same class while method overriding involves creating a subclass that overrides a method of its superclass.

Why Are the Pillars Important?

Object-oriented programming (OOP) has four pillars that are essential to its design. These pillars contribute to the benefits of OOP and why it is widely used in software development.

  • Encapsulation: This pillar is about keeping the data and functions that manipulate the data into a single unit called a class. This ensures that the data is protected from external access and can only be accessed through the methods provided by the class. Encapsulation promotes data security and reduces errors caused by data manipulation.
  • Inheritance: Inheritance allows new classes to be created based on existing ones. The new class inherits the properties and methods of the base class, and can also add or modify them. This saves development time and promotes code reuse.
  • Polymorphism: Polymorphism refers to the ability of an object to take on many forms. In OOP, this allows different objects to have the same interface or method signature while providing different implementations. This promotes flexibility and reduces code duplication.
  • Abstraction: Abstraction refers to the process of hiding implementation details while showing only the necessary information to the user. This promotes simplicity and reduces complexity, making it easier to understand and modify code.

These four pillars are important in OOP because they provide a strong foundation for software design that promotes flexibility, code reuse, data security, and simplicity. By adhering to these principles, developers can create more efficient, maintainable, and scalable software.

Commonly Asked Questions About the Pillars of Object-Oriented Programming

What is the difference between inheritance and polymorphism?

Inheritance and polymorphism are both important aspects of Object-Oriented Programming language. Inheritance is the mechanism that allows a new class to be derived from an old class. In other words, the new class can inherit all the members (data fields and methods) of the old class. In contrast, polymorphism is the ability of an object to take many forms. Through polymorphism, we can use a common operation in different ways. So, inheritance deals with class hierarchy, and polymorphism deals with the flexibility of a class.

What is the importance of encapsulation in OOP?

Encapsulation is a key feature of Object-Oriented Programming. It is the process of keeping the data hidden from the world and accessing it through specific methods. When an object contains hidden data, it is said to be encapsulated. Encapsulation provides data security and makes the code easy to manage. It enables us to control access to the object’s properties and methods, preventing unwanted changes to the object. Encapsulation also allows us to change the internal details of how an object works without affecting the rest of the code that uses it.


The four pillars of Object-oriented programming, namely inheritance, encapsulation, polymorphism, and abstraction, provide numerous benefits for software development. By breaking down code into objects that can interact in a structured manner, OOP helps to better manage software complexity, reduce errors, speed up development, and promote code reuse and extension in different applications. Inheritance allows for modular and reusable code, while encapsulation enables the hiding of private details of a class from other objects. Polymorphism fosters the use of a common operation in different ways, and abstraction allows for the creation of simplified models that can be easily used in various scenarios.


Source 1: Explanation of OOP Principles

Source 2: Examples of Encapsulation

Source 3: Difference Between Inheritance and Polymorphism

Being a web developer, writer, and blogger for five years, Jade has a keen interest in writing about programming, coding, and web development.
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