HTML

Web pages comprise of five basic layers:

1. Content
2. Semantics
3. Structure
4. Presentation
5. Behavior

Content refers to the text, images and multimedia components of web pages. Behavior refers mainly to JavaScript, which is covered in the page on JavaScript and AJAX. This page concentrates on the other three layers.

For all the effort you put into building your site, the most important thing to your users is how your site looks. Managing the inconsistencies in your theme for each browser, for each module, and for user selectable themes can be very challenging.

First you should familiarize yourself with basic Cascading Style Sheets (CSS) concepts. Review CSS Discuss or HTML dog for CSS resources. A good overview of the power of CSS can be seen at the CSS Zen Garden.