A persistent object store is a computer storage

Computer storage

Computer data storage, often called storage or memory, refers to computer components and recording media that retain digital data. Data storage is one of the core functions and fundamental components of computers....

 system that records and retrieves complete objects, or provides the illusion of doing so. Simple examples store the object's data in binary format, along with additional data defining its structure. More complex examples include object database

Object database

An object database is a database management system in which information is represented in the form of objects as used in object-oriented programming...

s or object-relational mapping

Object-relational mapping

Object-relational mapping in computer software is a programming technique for converting data between incompatible type systems in object-oriented programming languages. This creates, in effect, a "virtual object database" that can be used from within the programming language...

 systems, which combine a database

Database

A database is an organized collection of data for one or more purposes, usually in digital form. The data are typically organized to model relevant aspects of reality , in a way that supports processes requiring this information...

 system with support for easily storing objects. Many modern operating system

Operating system

An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

s provide some sort of support for "persisting" objects in flat files, often based on XML

XML

Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....

.