Joomla is a popular open-source content management system (CMS) developed in 2005, based on the earlier Mambo platform, allowing users to create a wide range of websites including corporate, educational, and personal sites. Key features include user management, media management, multilingual support, and extensive extensibility through various extensions like components, modules, and plugins. Joomla also has an organized development team focusing on continuous improvement and community support, ensuring users receive assistance and resources for effective implementation.