The database table prefix is a string (a few characters long) prepended to the name of Joomla!'s tables. Using a prefix enables you to run multiple installations of Joomla! using a single database. The database table prefix can be set during installation. Changing it later is possible, but requires access to the database through a non-Joomla medium or a Joomla Extension such as Akeeba Admin Tools and will cause some downtime. Extension developers need to use the string j73172_ to represent the prefix. This will be replaced by the real prefix during runtime by Joomla. Reference: http://docs.joomla.org/Glossary
An extension is a software package that extends your Joomla! installation in some way. A small selection of extensions is included with the default Joomla! installation but many more are available from the Joomla! Extensions Directory. The term extension is generic and the following specific extension types are available (listed alphabetically): Component (since ) – adds custom functions to your site that can be selected from menus Language (since ) – defines an additional language for your site Library (since ) – provides functions to be used by other extensions Module (since ) – shows nonessential data in a side box, possibly on multiple pages Package (since ) – bundles related extensions Plugin (since ) – modifies content in articles or provides functions to extend other extensions Template (since ) – define the look, feel, and navigation capabilities of your site For an overview of the most important extension types and the functionality they provide, see Extension types (general definitions) Reference: http://docs.joomla.org/Glossary
An optional file that allows the site administrator to override any language string in core Joomla or in an extension (other than installing a new language). There are two override files, one for the front-end and one for the administrative back-end.
