How are data and methods organized in an object oriented program?

When we talk about object oriented programming we say data and methods but why so?

•  The answer is that an object has some properties and that properties represent the data.Like

  Example:- Student object has some properties like name,age,roll_no etc so that is data about the  object.

  Lets see with program ,at this time do not bother about the code(if you are beginner):-

   class Student

   {

         String name;

         int age;

         int roll_no;

    }

         So you can see that a student can have name,age,roll_no etc. So this is data about the student.

• Now second come methods(functions),the methods are the operations which are performed on the data of the object.