Key features of Object Oriented Programming…

• Objects
• Classes
• Abstraction
• Encapsulation
• Inheritance
• Polymorphism

Objects :-

Objects are the basic run-time entities in an object-oriented programming. They may represents a person, a place, a bank account, a table of data or any item that the program has to handle. They may also represents user-defined data such as vector, time and lists. 

Classes:

Objects contain data, and code to manipulate that data. The entire set of data and code of an object can be made a user-defined data type with the help of class. In fact, objects are variable of the type class. Once a class has been defined, we can create a number of objects belonging to that class. A class is a collection of objects of similar type.

Ex. Vehicle car

Data Abstraction:

Abstractions refer to the act of representing essential features without including background details or explanation. They are commonly known as Abstraction Data Type(ADT).

Encapsulation:

The wrapping up of data and functions into single unit is known as encapsulation. Data encapsulation is a striking feature of a class. The data is not accessible to the outside world, and only those functions which are wrapped in the class can access it. These functions provide the interface between the object’s data and the program.

Inheritance:

Inheritance is the process by which objects of one class acquire the properties of object of another class. The class whose members are inherited is called the Base class and the class that inherits those members is called Derived class. 

Polymorphism:

Polymorphism is another OOP concept. Polymorphism means the ability to take more than one form. An operation may exhibit different behaviors at different instances.