TYPO3 is an open source CMS framework built in PHP. For starters, you can think of it as an enterprise WordPress. Initially, it provides you with a set of modules for content management, a WordPress-like page-tree panel and an editing panel allowing you to set the specifics of selected modules and pages.
As a TYPO3 administrator, you can assign roles to users and make sure they can only see and edit your CMS site on a per-needed basis. For working with media, documents and binaries, users are provided with the File Manager module, allowing them to add files, organize them by folders and access them during content creation quickly.
TYPO3 is developed and maintained by the TYPO3 Association and boasts a large community of personal, business, and enterprise users and contributors, including Philips, Leica, Lufthansa, and Mercedes-Benz.