\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