\chapter{Data Persistence}\label{persistence}The modules described in this chapter support storing Python data in apersistent form on disk. The \module{pickle} and \module{marshal}modules can turn many Python data types into a stream of bytes andthen recreate the objects from the bytes. The various DBM-relatedmodules support a family of hash-based file formats that store amapping of strings to other strings. The \module{bsddb} module alsoprovides such disk-based string-to-string mappings based on hashing,and also supports B-Tree and record-based formats.The list of modules described in this chapter is:\localmoduletable