No. Serialization is used whenever you want to preserve the state of an
object and/or transmit it across some type of boundary.
Writing the information to a file is one way to preserve the information and
you can definitely serialize for this reason. You might also want to
serialize and object before sending it across the internet such as a
webservice. Or you have out-of-process COM component (ServicedComponents)
which require that all passed information be serialized. Or, you can send
the data to a remote machine to be reconstructed and executed.
A recently project that I developed was a component that serialized an
object and encrypted it which was then saved to the registry.