What is CMS?

A content management system (CMS) is a computer software system for organizing and facilitating collaborative creation of documents and other content. A content management system is frequently a web application used for managing websites and web content, though in many cases, content management systems require special client software for editing and constructing articles. The market for content management systems remains fragmented, with many open-source and proprietary solutions available.

Other CMS aside from Joomla:

Typo3 - Open source content management system.
Xaraya - Open source content management system.
Plone - Open source content management system based on Zope and Python.
PostNuke - Open source content management system.
Vignette - Enterprise content management system.
Zope - Open source application server for building content management systems.
Textpattern - Open source content management system by Dean Allen.
PHPwcms - Open source content management system based on PHP and MySQL.
PHP-Nuke - Popular open source content management system based on PHP.
Xoops - Open source content management system based on PHP and MySQL..
Bricolage - Open source content management system.
CMSimple - Open source content management system.
DotNetNuke - Open source content management system based on ASP.NET.
WordPress - Open source content management system based on PHP and MySQL.
Drupal - Open source content management system.
eZ Publish - Open source content management system by eZ Systems.
Mambo - Open source content management system by Miro International.
Metadot - Open source portal server.
phpWebSite - Open source content management system based on PHP by the Web Technology Group at Appalachian State University.
RedDot - Enterprise content management system.
SPIP - Open source content management system based on PHP and MySQL by the minirezo.
Alfresco - Open source, J2EE-based content management system.
Site Executive - Content management system by Systems Alliance.
Vertical Site - Content management system based on J2EE by Enonic.
Back-End - Open source content management system for small/medium websites based on PHP and MySQL.
CMS400.NET - Content management system based on .NET by Ektron.
e107 - Open source content management system based on PHP and MySQL.
Freestyler - Content management system by Datalink.
NQContent - Content management system based on Coldfusion by NetQuest.
Kwiki - Open source wiki-type content management system based on Perl.
CityDesk - Content management tool by Fog Creek
Caravel - Open source content management system based on PHP.
QP7 - Content Management System by Quantum Art.
Tikiwiki - Open source content management system.
WebGUI - Open source content management system by Plain Black.
Website Baker - Open source content management system based on PHP.
SMBCMS - Small business content management system.
Miraserver - Content Management System based on PHP and MySQL by PC Media..
Artiphp Velocity - Open source content management system. Also called ArtiVelocity or Artiloo.
AssetNow - Content management system by Orbital.
Clever Copy - Free content management system based on PHP and MySQL.
Colony - Content management system to create accessible websites by Red Ant Development.