This document discusses CSS and HTML tables. It begins by explaining how to link an external CSS stylesheet to an HTML page and how changes to the external stylesheet will update all linked pages. It then covers using ID and class selectors in CSS to style specific elements on a page. The document concludes by describing the basic structure of an HTML table using <table>, <tr>, and <td> tags and different attributes that can be used to control table formatting and cell alignment, spacing, and spanning.