Definition of 'pickle'

[anson]

Dear people,

I don't understand the definition provided in the Python documentation
for 'pickle':

The pickle module implements a fundamental, but powerful algorithm for
serializing and de-serializing a Python object structure. ``Pickling''
is the process whereby a Python object hierarchy is converted into a
byte stream, and ``unpickling'' is the inverse operation, whereby a
byte stream is converted back into an object hierarchy. Pickling (and
unpickling) is alternatively known as ``serialization'',
``marshalling,''3.2 or ``flattening'', however the preferred term used
here is ``pickling'' and ``unpickling'' to avoid confusing.

thanks!

zeallous