Serialization is the process of converting a set of object into a linear stream of bytes, which can then be sent through a socket or stored in a file, or simply manipulated as a stream of data. Serialization is the mechanism used by RMI to pass objects between JVMs, either as arguments in a method invocation from a client to a server or as return values from a method invocation .De-Serialization is process to revert back this stream into java objects.