Joomla is an award-winning content management system (CMS), which enables you to easily build many types of website. Best of all, Joomla is an open source solution that is freely available to everyone.
Joomla! sits half-way between WordPress and Drupal, being both flexible and easy to learn.
Things You Must Know Content Index :--
Joomla Overview, installation + Configuration
Joomla Administration Part 1
Joomla Administration Part 2
Joomla Administration Part 3
Joomla Theme Development Part 1
Variable, template Function etc.,
Joomla Theme Development Part 2
Customization, twicking etc.,
Joomla Theme Development Part 3
Advance theming including plugin output customization etc.,
Joomla Add-on/Plugin Development Part 1
Joomla Add-on/Plugin Development Part 2
Joomla Add-on/Plugin Development Part 3