Controlling page layout
In the early days of web development, the most common way to lay out a page was to use a table. Modern best practices, based on web standards, dictate the separation of presentation from content, which rules out the use of tables as layout tools.
Microsoft Expression Web provides two ways to simplify the task of controlling page layout: cascading style sheets and dynamic web templates. Layouts based on cascading style sheets are the basic building blocks that define page layout regions.
Dynamic web templates, which often include layouts based on cascading style sheets, help you apply the same appearance to several pages in your site without having to manually build each page.