Object-oriented programming (OOP) is a programming language model organized around objects rather than “actions” and data rather than logic. Within the OOP concepts in C++, the four pillars that define the concept are Abstraction, Encapsulation, Polymorphism, and Inheritance.

Abstraction: Abstraction is an essential concept of object-oriented programming that helps simplify complex real-world problems by reducing them to more abstract levels. Abstraction is the process of hiding the implementation details from the user, thereby only presenting the functionality. This allows the user to work with their application without worrying about the underlying implementation details.

Encapsulation: Encapsulation is a process of enclosing one or more items within a physical or logical package. It is an OOP concept that hides the properties and behaviors of an object from the outside world. This means that an object’s members variables and methods are hidden from other objects, thereby allowing only the object to have access to them.

Polymorphism: Polymorphism is an object-oriented programming concept that allows an object to take different forms of behavior. It allows a single object to act in a variety of different ways, depending on the context. This helps a programmer make the best possible use of objects by allowing them to be reused in multiple situations.

Inheritance: Inheritance is a powerful tool that helps a programmer create a family of objects that share similar characteristics. It allows the programmer to use the existing class and extend it to create a new class. This new class inherits all the features of its parent class, but can also include additional features as needed.