This document provides an overview of CSS3 modules including Backgrounds and Borders, Multi-column Layout, Selectors, Grid Positioning, and Media Queries. It discusses new CSS3 features like advanced border properties, multi-column page layout without additional markup, more robust selector options, grid-based page layout, and media query enhancements. Examples are given to illustrate how these features can be used. Resources for learning more about CSS3 are also listed.