A content management system (CMS) is a computer application used to create, edit, manage, and publish content in a consistently organized fashion. CMSs are frequently used for storing, controlling, versioning, and publishing industry-specific documentation such as news articles, operators' manuals, technical manuals, sales guides, and marketing brochures. The content managed may include computer files, image media, audio files, video files, electronic documents, and Web content.
http://en.wikipedia.org/wiki/Content_management_system

open source content management system to create, edit, publish and manage content in a consistent and organized fashion with our admin control panel.

It is an Open-Source Content Management System (CMS) that is written in PHP and powered by MySQL. It does not only help you manage your personal blog but also maintain your postings at social networks.

AdaptCMS is an open source CMS that has always strived to provide the idea of being useable on any content website along with great support and continued updates. With custom fields, social functions and more you can create any website you want.

ALPHA CMS 10.0 and ALPHA Framework 10.0 is the most complete and advanced system ever developed!
ALPHA CMS and ALPHA Framework is a killer web application / system that can support huge projects.
ALPHA CMS is written in PHP and MySQL.

Anantasoft Gazelle CMS is a free open source CMS solution, which is fully W3C HTML 1.0 strict compliant, Search Engine Friendly and easily extendable with modules and templates.

A small and very fast to manage content management system that probably is aimed particularly at technology nerds who love the powers of HTML5 and AJAX as much as I do.

appRain is one of the first officially released Open-source Content Management Framework (CMF).

ArticleSetup is the powerful, flexible, and surprisingly simple web software that you can use to setup your own article directory. And, it's completely free! Built with PHP/MySQL, this script is easy to use, customizable, feature-rich, and fully supported

AutoCMS,The Best Landing Page,lightweight,smaller and Opensource CMS with all the necessary in the minimal space!

Automne, a free open-source content management system (CMS) writen in PHP. You can use it to create your website freely and easily.