Extension 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
Language Pack An installable language extension that provides the option to view a Joomla site in a different language. Language packs can be for the front or back end of the site. With Joomla!, language-files are stored within the folder languages, and within that directory for each language a subdirectory is created.
Model One of the three elements of the model-view-controller design pattern. The model encapsulates the data used by the component. The model is typically all about the “business” or “domain” logic and the database. The base API class we use for models is called JModel.
