# Grav CMS > Grav is an open-source, API-first flat-file CMS written in PHP. Content is stored as files on disk rather than in a database, which means no database server to run, plain-text content that lives in Git, and a full site that can be copied or deployed by moving a folder. Grav 2.0 ships a first-party REST API, so the same install can serve traditional server-rendered pages, run headless as an API-only backend, or do both at once. Grav is released under the MIT license and is free to use. It runs on Linux, macOS and Windows, and needs only PHP and a web server. ## What Grav is - [Homepage](https://getgrav.org/): overview of Grav 2.0 and what it is for. - [Tour](https://getgrav.org/tour): guided walkthrough of how Grav works, page by page. - [Features](https://getgrav.org/features): capability list for Grav 2.0. - [About](https://getgrav.org/about): project history, team and licensing. ## API and headless use - [The Grav API: The Foundation of 2.0](https://getgrav.org/blog/grav-2-api): what the first-party REST API covers and why it was built. - [Integrating with the Grav API](https://getgrav.org/blog/grav-2-dev-api-integration): using the API from a plugin or an external client. - [Grav 2.0 Released](https://getgrav.org/blog/grav-2-stable-released): the 2.0 release, covering the API-first core, the new admin and native AI support. - [Admin Next](https://getgrav.org/blog/grav-2-admin-next): the new admin, built entirely on the public API. ## Documentation and source - [Documentation](https://learn.getgrav.org/): full user, developer and API documentation. - [Source on GitHub](https://github.com/getgrav/grav): Grav core repository. - [Downloads](https://getgrav.org/downloads): core packages, plus the plugin, theme and skeleton directory. ## Extending Grav - [Plugins and themes](https://getgrav.org/downloads/plugins): the package repository served to Grav's package manager. - [Grav Premium](https://getgrav.org/premium): commercially supported first-party plugins and themes. ## Optional - [Blog](https://getgrav.org/blog): release announcements and development notes. - [Discord](https://discord.gg/grav): community chat and support.