# Distributed File System Distributed File System (ExDFS) is shared data storage and serves as an main support module for ExtraChain DAO Framework. Distributed File System can be used in various ways. It can: * Hold user data of DAO-project * Distribute files between users * Authorize access to files * Differentiate access rights for users One of main ExDFS elements is Historical Chain. Historical chain is a data structure that holds all changes made in particular file, including creation and removal. Historical chains are used to: * Contain data changes * Organize data changes * Order changes in a non-time-based way * Secure data changes (changes are non-removable) * Proof of Existence (file can be retrieved on each state of change) All these possibilities create stable and protected distributed file storage that can hold any amount of files without corrupted links, order and state errors. ExDFS is protected by cryptographic methods of ExtraChain and allows to build secured and anonymized decentralized apps, without any need in localized data storage. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.extrachain.io/overview/distributed-file-system.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.