Tiki Content Management System or Groupware which is more commonly termed as TikiWiki; is an open source Content Management System (CMS) / Geospatial Content Management System (GeoCMS) / Groupware web application enabling websites and portals on the internet and on intranets and extranets.
Moodle is a free software e-learning platform also termed as a Course Management System (CMS), Learning Management Systems (LMS), or Virtual Learning Environment (VLE).
WordPress is a blog publishing system (or a Weblog software) written in PHP and is backed by a MySQL database. It is a top-of-the line publishing platform emphasizing on advanced utility, web standards as well as aesthetics.