The Joomla CMS is a free, open-source content management system used by millions of designers, developers, and web administrators worldwide. The system currently has almost 5,000 extensions available in it's Extensions Directory (http://extensions.joomla.org/), many of which are released under the GPL (non-commercial, also known as free) license. While a Joomla core install has many options and parameters available out of the box; functionality such as site backups, advanced optimization tools for search engines, and file/content editors aren't included. Working with Joomla for the past two years, I've created this list of five extensions that are essential for almost every Joomla website.
1. Akeeba Backup (formerly JoomlaPack)

One of the most important extensions for any website is a backup system. Akeeba Backup (formerly known as JoomlaPack) provides an easy to use solution to backup your Joomla website. The component creates a full installable backup of a Joomla site, as well as offering options to backup just the mysql database, files, and directory exclusion. The developers also created a custom file format (.jpa for Joomla Pack Archive) to increase compression and backup speed. The .jpa format allows easy installs using the Kickstart system, as well as options to fine tune backup details and backup scheduling. AkeebaBackup is a free (non-commercial) extension.