The Module Class Suffix can be configured in the Advanced Options of the Module Manager for each module individually. Background colors, borders, padding and margins can all be controlled through this setting. In addition, almost any aspect of text can be controlled this way, from colors and weights to sizes and font families.
One common usage for Module Class Suffixes is to create a "Featured" module that has colors and heading styles that are set apart from the rest of the standard modules on the page. Using this method, it's easy to create an item such as a "call to action."
{jb_purplebox} Joomla Modules are explained in lesson 9 our free Joomla tutorial course - The Basics. {/jb_purplebox}
