Object-Oriented Programming (OOP) is a programming paradigm based on the concept of "objects," which are instances of classes that encapsulate data and behaviors. In OOP, objects interact with one another to perform tasks, making the code more modular, reusable, and easier to maintain. OOP principles include inheritance, polymorphism, encapsulation, and abstraction, which help in organizing and structuring software in a way that mimics real-world systems. Popular programming languages that support OOP include Java, C++, Python, and Ruby. OOP has become one of the dominant programming paradigms in software development due to its ability to manage complex systems and improve code organization.