Object-Oriented Programming (OOP) is the term used to describe a programming approach based on objects and classes.

C++ provides various concepts like

  • Objects
  • Classes
  • Data Abstraction
  • Encapsulation
  • Inheritance
  • Polymorphism
Objects:
An object is an instance of a class. Objects are the basic run time entities in an object-oriented system.

Class:
Class is a blueprint of an object. A class is a definitive Description of a group of objects with similar properties and behaviors. Class is a user-defined data type.

Data Abstraction:
Abstraction refers to the act of representing essential features without including the background details or explanation.

Encapsulation:
The wrapping up of data and function into a single unit (called class) is known as encapsulation.

Inheritance:
Inheritance is the process by which objects of one class acquire the properties of objects of other  classes.

Polymorphism:
Polymorphism, a Greek term, where poly means many and morph means forms.
It can be exhibited via operator overloading or function overloading.
The process of making an operator to exhibit different behaviors in different instances is known as operator overloading. 
Using a single function name to perform different type of task is known as function overloading.


Data types can be classified as follows:

1. Primitive / Built-in Datatypes 
    int, char, float, double, boolean 

2. Derived Datatypes
    Functions, arrays, pointers, references

3. Abstract / User-defined Datatypes
    Class, Structure, Union, Enumeration