A split menu is where different levels of a single menu are displayed in two or more locations on a single web page.

For example, a common requirement is for a menu of top-level items to appear at the top of the page. When one of the items is clicked the user is taken to a page where a secondary menu, say on the left of the page, shows second-level items within the scope of the top-level item.

The menus appear in separate locations on the page, but are related because one shows only top-level items while the other shows second-level items.

This idea can be extended to include menus for third-level items and beyond.

This can be implemented in Joomla using a single multi-level menu then creating more than one menu module each referring to a different level.

Reference: http://docs.joomla.org/Glossary

The process of optimizing your pages to give them high-ranking placement in the search results page of a search engine (SERP) - including Google, Bing, Yahoo and other search engines.

Search-engine friendly URLs. Refers to URLs that are descriptive in a way that search engines can understand. Normal Joomla! URLs look something like this: http://www.yoursite.org/index.php?option=com_content&view=section&id=3&Itemid=41

You can optionally have URLs display to look like static HTML pages like this: http://www.yoursite.org/faq.html

Joomla! 1.5 has built-in optionos for SEF URLs. These are enabled by changing the ""SEO Settings"" in the Site tab in the Global Configuration screen in the Joomla! back-end. There are also third-party extensions that create SEF URLs for Joomla!.

Reference: http://docs.joomla.org/Glossary

Languages are perhaps the most basic and critical extension type. Languages are packaged as either a core language pack or an extension language pack. These packages consist of INI files which contain key/value pairs. These key/value pairs provide the translation of static text strings within Joomla! source code. This allows both the Joomla! core and third party components and modules to be internationalised. Core language packs also include an XML meta file describing the language and providing information about the fonts to use for PDF content generation.

Reference: http://docs.joomla.org/Glossary