Object-Oriented Programming (OOP) is a programming paradigm that uses objects to represent data and methods. It allows developers to create modular and reusable code by encapsulating properties and behaviors within objects, making it easier to manage complex software systems. In OOP, key concepts include classes, objects, inheritance, and polymorphism. These principles help in organizing code in a way that mirrors real-world entities, promoting better collaboration and maintainability in software projects.