A scripting language that runs inside the client browser, used in many web applications. In Joomla, JavaScript has become an important part to enhance the user interface and provide AJAX functionality.

Module chrome is a term for PHP functions that provide some optional HTML markup in which the module code is placed. This is often called a wrapper for the module output.

Module chrome allows template designers to have a certain amount of control over the way the output from a Module is displayed in their template. Essentially, it consists of a small amount of predefined HTML which is inserted before, after, or around the output from each module, and which can then be styled using CSS. Module chrome is commonly used to provide borders around modules, especially with rounded corners, but it can be used for much more than that.

Module chrome is determined by using the 'style' attribute in the statement calling the module. For example, the following statement may be used in the index.php file of a template to insert the Modules in the 'user1' position and apply the 'custom' Module chrome:

<jdoc:include type="modules" name="user1" style="custom" />

It can be seen that the same Module chrome is applied to every Module in that position - in other words, if you want to have two Modules in a column, but want them to have different Module chrome, then they would need to be set up as two different 'positions' (e.g. 'user1' and 'user2').

The standard Joomla! 1.5+ package includes six default Module chrome styles. However, the flexibility of the template system means that you are not limited to these styles - it's very easy to create as many new styles as you want!

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

In Joomla! an Article is a piece of content consisting of text (HTML), possibly with links to other resources (for example, images). Articles are the basic units of information in the content system and the bottom level in the content hierarchy. Since Joomla! 2.5 , each Article is in exactly one Category. A Category can be in another Category making it a sub Category. It is also possible to have Uncategorised Articles. These articles exist without being associated with any Category.

Before Joomla! 2.5 and earlier versions, an Article was the third level in the hierarchy Sections ? Categories ? Articles. Now an Article is a bottom level and will alway be the second level or greater in hierarchy.

Category ? Articles
Category ? sub Category ? Articles
Category ? sub Category ? sub Category ? Articles

Articles are maintained using the Article Manager (see the Content Article Manager for or the Content Article Manager for ) which can be reached in the Administrator (Back-end) by clicking on the Content menu, then the Article Manager menu item.

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