\chapter{Data Persistence} \label{persistence} The modules described in this chapter support storing Python data in a persistent form on disk. The \module{pickle} and \module{marshal} modules can turn many Python data types into a stream of bytes and then recreate the objects from the bytes. The various DBM-related modules support a family of hash-based file formats that store a mapping of strings to other strings. The \module{bsddb} module also provides 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