What is oops / oops concept?

In java ,It is a most regular asked question for fresher and experience people. But all people knows the answer.but all make mistake to give answer perfectly.Remember one thing if you have experience then you should know that you have to give Real rime example always.
 So what would be the answer....
oop is nothing but a object oriented programs.In java basically we considered as 4 element in oops.i.e

• Abstraction
• Encapsulation
• Inheritance
• Polimorphism

I am saying some briefly about it .

.Abstraction nothing but it is a concept of hiding internal element and just highlight the set up services.

If i go through the project then considered ATM , 

We developer are not showing the internal implementation what we are doing for ATM,we only showing the setup servcies in ATM GUI screen.

--Advantage Of Abstraction:

1. We are achieving security (Because we are not highlighting the internal implementation).
2. Our enhancement becoming easy(Because we can perform any kind of changes in our internal system without affecting outside person)
3. we can improve our easyness to use our system.
4. Another thing is we can improve maintanability of the application.

.Encapsulation  is nothing but binding the data and corresponding method into as ingle unit

--Advantage is we can achieve security and 

main disadvantage is it increses the length of code and slows down the excution.

.Inheritance is also known as IS A RELATIONSHIP .By using extend keyword we can implement Inheritance from a parent class to a child class.
--Advantage of Inheritance is Code reusability.

.Polymorphism is  nothing but one name but multiple forms.
Realtime example is One Interface having multiple methods and One name having multiple Forms .