Answer:
Object-oriented programming (OOP) is a procedural language and based on classes associated with an object. Without classes and object relationship OOP is not possible. According to program's design concept classes provide abstraction and encapsulation with the help of object. Object have states and behaviors like cat has states like name, color and cat has also behaviors like wagging the tail, eating, jumping etc. A class forms template or blueprints for these states and behaviors because different cats have different behaviors and states.
Methods provide a way for encapsulation and accessing private class members with public methods and static fields are sometimes best alternative for global variable. We can use static field when it same for all and shared by all objects of that class and it can save memory because we do not have to initialize it for each object
