The four pillars are Encapsulation (bundling data with the methods that operate on it), Inheritance (reusing behavior from a parent class), Polymorphism (one interface, many implementations), and Abstraction (hiding implementation details behind a simpler interface).

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#OOP#Encapsulation#Inheritance#Polymorphism#Abstraction

Quick Summary

Encapsulation: hide internal state behind getters/setters. Inheritance: a subclass reuses/extends a superclass's fields and methods. Polymorphism: the same method call behaves differently depending on the actual object type. Abstraction: expose only what's necessary, hide the rest behind interfaces/abstract classes.

The Four Pillars of OOP: Encapsulation · Inheritance · Polymorphism · Abstraction

Interview Answer

Encapsulation protects internal state, inheritance enables code reuse across a class hierarchy, polymorphism lets one interface represent many implementations at runtime, and abstraction hides complexity behind a simple contract — together they're what makes OOP systems modular and maintainable.