High Quality Content by WIKIPEDIA articles! In the computer programming language Python, pickle is the standard mechanism for object serialization; pickling is the common term among Python programmers for serialization (unpickling for deserializing). Pickle uses a simple stack-based virtual machine that records the instructions used to reconstruct the object. This makes pickle vulnerable to security risks by malformed or maliciously constructed data, that may cause the deserializer to import arbitrary modules and instantiate any object. Also, not all objects can be pickled, especially ones that hold operating system resources like file handles.