Joomla is a free, open-source content management system (CMS) for building websites and online applications. Joomla uses PHP and a MySQL database. It lets one or many users create, edit, organize and publish web content through a browser-based administrator interface. Joomla renders the public site separately. Joomla is released under the GPL, and a volunteer community maintains it. The same code base includes a general-purpose framework that can run independently of the CMS.
Articles, categories and tagging
The core content type in Joomla is the article. Authors write articles in a WYSIWYG editor (TinyMCE by default) that lets them format text, insert media and apply editor buttons without writing code. Articles belong to categories, which can be nested to any depth. Tags can also label articles to group related items across the category tree. Custom fields extend articles, users and contacts with fifteen field types. They let users attach structured data such as specifications or extra author details to ordinary content.
Content versioning keeps earlier revisions of an article so editors can review or restore changes. Publishing tools let editors choose when to publish an article. Editors can also work from the front end, editing a page while viewing it on the live site. The media manager handles uploaded images and files, with drag-and-drop insertion into the editor.
Menus and page assembly
A menu item selects a component to render a Joomla page’s main content. Modules surround that content in positions the template defines. A site can have as many menus and menu items as it needs. Each item decides what the central area shows: a single article, a category list, a contact form, search results and so on. Most of a Joomla site’s structure comes from this separation of menu, component and modules.
The extension system
Joomla treats its framework as an operating system and extensions as the applications that run on it. Components are the largest type and behave like mini-applications with both a public side and an administrator side. A menu item triggers a component to produce the body of the page, as the built-in article component does. Modules are lighter blocks — a login form, a menu, a footer — assigned per menu item and arranged around the component output. Plugins are event handlers that run when the core, a module or a component fires an event, for example filtering text in a submitted article.
Templates control the design and language extensions translate the interface, completing the main set of types. The Joomla Extensions Directory lists thousands of additional extensions and templates, most of them free under the GPL. Users can find and install many of them directly from the administrator through the install-from-web feature.
Templates and layout
Templates set the look of a Joomla site and declare the positions where the single component and any number of modules appear. Template assignment applies different templates to different pages, so a landing page and an article page can look distinct. Template overrides can adjust output by changing how a component or module renders. They leave core files untouched and so survive updates. The shipped templates use Bootstrap for responsive layouts that adapt to phones, tablets and desktops. They support LESS for styling; sites can also build custom templates or adopt an external template framework.
Users and access control
Joomla supports multiple users with different permission levels through an access control list (ACL). Users belong to groups. Access levels decide which content and which administrative actions each group can reach, from a visitor who can only read to editors, publishers and administrators. Visitor self-registration can grant additional access after sign-up when enabled. Administrators can exchange private messages within the backend.
Multilingual sites
Joomla publishes content in many languages from a single installation. Language packs translate both the front end and the administrator. Associating items across languages lets Joomla serve the correct version and lets visitors switch between them. Search-engine-friendly URLs and built-in SEO settings apply across the site.
Built-in content tools
Beyond articles, Joomla ships with several content components. Contacts manages people, departments and contact forms. Banners adds banners or advertisements to the site. News feeds pulls in external RSS feeds while syndication publishes the site’s own content as a feed. Redirects map old or broken URLs to working addresses, and Smart Search helps visitors find content. Caching improves page-load speed on busier sites.
Updates and maintenance
Joomla updates its core with a single action from the administrator. Extensions that support the update system can stay current the same way. Users can locate and install new extensions from the web without leaving the backend. These maintenance tools aim to let a site owner run the site after a developer or agency has built it. Contextual in-application help and the documentation wiki share this aim.
Framework for developers
Underneath the CMS, Joomla uses a model-view-controller (MVC) architecture with a flexible routing system for handling URLs. Developers can use the Joomla Framework on its own to build web and command-line applications. The project gives inventory control systems, data reporting tools, product catalogs, business directories and reservation systems as examples. A microdata library adds structured data, published coding guidelines cover secure development, and Joomla runs on PHP 8.
