While it is possible to build a simple table quickly, complex tables with varying border styles, running headers and footers, and column-based layout were not easily constructed from the old HTML 3.2 table model. Microsoft rectified this inadequacy somewhat by adding a number of table-layout controls to Internet Explorer Version 3.0. These very useful extensions found their way into the HTML 4 standard and subsequently into XHTML. They provide row-based grouping and running headers and footers, along with column-based layout features.
There is good news and bad news about these table features, of course. They provide a nice way to make your tables more attractive and presentable, but they currently work only within Internet Explorer and Netscape 6. If you choose to use them, make sure your tables stand up with the older browsers, too.