Object-Oriented Programming (OOP) is a programming paradigm that uses "objects" to represent data and methods. An object can be thought of as a self-contained unit that combines both data (attributes) and functions (methods) that operate on that data. This approach helps organize code in a way that makes it easier to manage and understand, especially in large software projects. In OOP, key concepts include classes, inheritance, and polymorphism. A class is a blueprint for creating objects, while inheritance allows one class to inherit properties and methods from another, promoting code reuse. Polymorphism enables objects to be treated as instances of their parent class, allowing for flexible and dynamic code behavior.