Explain all the features of Object Oriented Programming System (OOPS).

Object-Oriented Programming (OOP) is a programming paradigm that enables you to organize code by creating objects that have properties and methods. The following are the key features of Object-Oriented Programming:

1. Abstraction:
   Abstraction is the process of identifying and defining the essential characteristics of an object, and ignoring the rest. In OOP, abstraction is implemented using classes and interfaces.

2. Encapsulation:
   Encapsulation refers to the act of hiding data and methods that operate on that data within a class, to prevent unauthorized access and modification. This feature is achieved by making variables and methods private or protected.

3. Inheritance:
   Inheritance is a mechanism by which one class inherits the properties and behavior of another class. The class that is being inherited is known as the parent or super class, while the class that inherits is known as the child or sub class.

4. Polymorphism:
   Polymorphism is the ability of objects of different types to be treated as if they were of the same type. This feature is implemented through method overriding and method overloading.

5. Classes and Objects:
   OOP revolves around the concept of objects, which are instances of classes. A class is a blueprint or template for creating objects, which defines their properties and behavior.

6. Message Passing:
   In OOP, objects communicate with each other by sending and receiving messages. A message is a request for an object to perform a certain action, and the object responds by executing the appropriate method.

Overall, OOP provides a modular and organized way of writing code, making it easier to maintain, extend and reuse the code.