Instead of using tables or Layout mode to create your layout, some web designers prefer to work with AP elements. Dreamweaver enables you to create your layout using AP elements, then (if you want) convert them into tables. For example, you might need to convert your AP elements to tables if you need to support browsers before version 4.0. Converting AP elements to tables, however, is highly discouraged because it can result in tables with a large number of empty cells, not to mention bloated code. If you need a page layout that uses tables, it is best to create that page layout using the standard table layout tools available in Dreamweaver.
You can convert back and forth between AP elements and tables to adjust the layout and optimize page design. (When you convert a table back to AP elements, however, Dreamweaver converts the table back to AP Divs, regardless of the type of AP element you might have had on the page before the conversion to tables.) You cannot convert a specific table or AP element on a page; you must convert AP elements to tables and tables to AP Divs for an entire page.