In Java, serialization is the process of converting the state of an object into a byte stream, which can be used to recreate the actual Java object in memory. Serialization is used to persist or save an objects state, and the byte stream created is platform-independent, meaning that the object serialized on one platform can be deserialized on a different platform. To make a Java object serializable, we implement the java.io.Serializable interface.

A Java object is serializable if its class or any of its superclasses implements either the java.io.Serializable interface or its subinterface, java.io.Externalizable. When an object is serialized, information that identifies its class is recorded in the serialized stream, but the classs definition ("class file") itself is not recorded. It is the responsibility of the system that is deserializing the object to determine how to locate and load the necessary class files.

Some key points to remember about serialization in Java include:

• Serialization is a marker interface with no method or data member.
• All the fields of a class must be serializable; otherwise, use the transient keyword.
• The child class doesnt have to implement the Serializable interface if the parent class does.
• The serialization process only saves non-static data members, but not static or transient data members.
• By default, the String and all wrapper classes implement the Serializable interface.

In summary, serialization in Java is a mechanism for converting the state of an object into a byte stream, which can be used to recreate the actual Java object in memory. To make a Java object serializable, we implement the java.io.Serializable interface.