Object-Oriented Programming is a paradigm that organizes software design around objects rather than functions and logic, bundling data with methods that operate on that data. It emerged in the 1960s and became mainstream through languages like Smalltalk, C++, Java, and Python, fundamentally changing how developers structure reusable, maintainable code. At its core, OOP is built on four foundational pillars—encapsulation, inheritance, polymorphism, and abstraction—that together enable modeling real-world problems as interacting objects. Understanding when to favor composition over inheritance and recognizing common anti-patterns like God Objects are crucial for writing clean, scalable object-oriented systems.