Serializable is a standard Java interface. Parcelable is an Android specific interface where you implement the serialization yourself. It was created to be far more efficient than Serializable (The problem with this approach is that reflection is used and it is a slow process. This mechanism also tends to create a lot of temporary objects and cause quite a bit of garbage collection.).

Serialization Serialization is the process of converting an object into a stream of bytes in order to store an object into memory, so that it can be recreated at a later time, while still keeping the object's original state and data.

How to disallow serialization? We can declare the variable as transient.