wordpress: modifying themes

A WordPress "theme" is a collection of documents, generally consisting of:

• One or more CSS style sheets
• Any necessary images that comprise the theme graphics
• A collection of PHP/HTML "template" files
• A thumbnail image representing the theme in the Dashboard

A typical WordPress theme contains a dozen or more files, but only a few are technically required.

These files work together as a package to define the entire look and feel - and sometimes behavior - of a WordPress site. Themes are completely decoupled from site content, so in theory, a site owner can apply a new theme with the click of a button and have all content on their site take on a whole new appearance (in practice, site redesigns aren't quite this simple).

This collection of files is contained in a folder that lives in the wp-content/themes directory on your web server. When an administrator visits the Appearance | Themes section of the WordPress Dashboard, all valid theme folders in that location will appear. Any valid theme can be applied to the site content by clicking the Activate link below its name.