Serialization is a platform-independent mechanism for writing the state of an object into a byte-stream. For serializing the object, we call the
writeObject() method of java.io.ObjectOutputStream class. Only classes that implement Serializable or extend a
class that does it can successfully be serialized (or de-serialized).
Attempting to write a class with the writeObject method of the ObjectOutputStream class that does not implement
Serializable or extends a class that implements it, will throw an IOException.
