Define blueprints (classes) and create instances (objects).
A class is a user-defined data type that acts as a blueprint for creating objects. It encapsulates data (attributes, implemented as member variables) and methods (behaviors, implemented as member functions) that operate on that data. For example, you could define a `Dog` class. Its attributes might be `name`, `breed`, and `age`, and its methods could be `bark()`, `wagTail()`, and `fetch()`. The class definition itself doesn't create any dogs; it just describes what a dog is. An object is a concrete instance of a class. Once a class is defined, you can create multiple objects from it. For example, `Dog myDog;` creates an object named `myDog` of the `Dog` class. Each object has its own set of member variables. So, if you create another object, `Dog neighborDog;`, it will have its own `name`, `breed`, and `age`, separate from `myDog`. You access the members (variables and functions) of an object using the dot (`.`) operator. For example, `myDog.name = "Fido";` would set the name of the `myDog` object, and `myDog.bark();` would call its `bark` method. This bundling of data and functionality is a core principle of OOP and helps in creating well-structured, logical programs.