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 mechanism that offers users a stored view of (part of) a web page so that does not have to be pulled from the database. Joomla core offers three levels of caching: Page caching View caching Module caching. By default, Joomla does not cache any content. When caching is switched on, the stored views for this are stored in the filesystem for Joomla ../cache/page/ folder.
A Cascading Style Sheet or CSS is used to control the presentation of an XHTML page. For example, a CSS file will often control the font, margins, color, background graphics, and other aspects of a web page's appearance. CSS allows you to separate the content of an XHTML page from it's appearance. In Joomla!, CSS files (for example, template.css) are normally part of the template. Reference: http://docs.joomla.org/Glossary
