Object-Oriented Programming (OOP) is a programming paradigm based on the concept of "objects," which are instances of classes that encapsulate data and behavior. In OOP, the structure of a program is organized around these objects, rather than actions or logic. Each object represents a real-world entity and can interact with other objects in the system, making the code more modular, reusable, and easier to maintain. OOP principles include encapsulation, inheritance, polymorphism, and abstraction, all of which contribute to creating a well-structured and flexible codebase.

Encapsulation involves bundling the data (attributes) and methods (functions) that operate on the data within a single unit, or class, and controlling access to that data through access modifiers. Inheritance allows new classes to inherit properties and methods from existing ones, promoting code reuse and reducing redundancy. Polymorphism enables objects to be treated as instances of their parent class, allowing for flexible and dynamic method invocation. Abstraction simplifies complex systems by exposing only the relevant details to the user while hiding the underlying implementation. OOP is widely used in modern programming languages such as Java, C++, Python, and Ruby, and is particularly well-suited for large-scale software development projects.