Drupal similar to Joomla is also a open sourced Content Management System (CMS) written in PHP but is often used more for back-end systems with a focus on business collaboration and knowledge management platforms.  The standard build of Drupal contains many common CMS features such as the ability to register and maintain individual user accounts but offers a flexible but rich privilege/permissions system.  Other included features such as rss-feed, customised pay layouts, creation and menu management, and tied into an administration system.

Some of the options that web designer can assist with is in the creation of brochure websites, multi-user blogs, community forums and even user generated content within a community driven website.  If you need more extensive features, web developers can assist if you require new features or custom behaviour which Drupal allows in order to extend its CMS core capabilities.  The plugin modules are referred to as Contrib Modules and your developers may refer to web application framework as Drupal can be defined as a Content Management Framework because it offers sophisticated programming interfaces for developers.

Drupal can run on any hosting platform that is capable of running PHP version 3.4.5 and a database such as PostgreSQL or MySQL which stores content and site settings.