Cache / Caching
Cached files are those that are saved or copied (downloaded) by a web browser so that the next time that user visits the site, the page loads faster.
CMS (Content Management System)
Also known as a CMS, the Content Management System is a backend tool for managing a site’s content that separates said content from the design and functionality of the site. Using a CMS generally makes it easier to change the design or function of a site independent of the site’s content. It also (usually) makes it easier for content to be added to the site for people who aren’t designers.
CSS (Cascading Stylesheets)
Also referred to simply as CSS, Cascading Style Sheets are used to define the look and feel of a web site outside of the actual HTML file(s) of the site. In recent years, CSS has replaced tables and other HTML-based methods for formatting and laying out websites. The benefits to using CSS are many, but some of the most important are the simplification of a site’s HTML files (which can actually increase search engine rankings) and the ability to completely change the style of a site by changing just one file, without having to make changes to content.