XHTML allows tables to span columns and rows to create more complex layouts. Spanning columns uses the colspan attribute to make a cell stretch across multiple columns. Spanning rows uses the rowspan attribute to make a cell stretch across multiple rows. This allows non-uniform grids to group or split cells across rows and columns.

1. Advanced Tables

2. Spanning Columns and Rows: So far, our tables have been relatively simple, with a uniform grid of rows and columns: XHTML allows us to create more complex table elements by spanning specified rows or columns:

3. Spanning Columns: <table width=&quot;300&quot; border=&quot;1&quot;> <tr> <td colspan=&quot;3&quot; >Span 3 Columns</td> </tr> <tr> <td>R2C1</td> <td>R2C2</td> <td>R2C3</td> </tr> <tr> <td>R3C1</td> <td>R3C2</td> <td>R3C3</td> </tr> </table> By adding the colspan=&quot;3&quot; to the <td> element, we are telling the browser that we want to stretch a single table cell across the space of three columns. R3C2 R2C2 R3C3 R3C1 R2C3 R2C1 Span 3 Columns

4. Spanning Rows: <table width=&quot;300&quot; border=&quot;1&quot;> <tr> <td rowspan=&quot;3&quot; >Span 3 Rows</td> <td>R1C2</td> <td>R1C3</td> </tr> <tr> <td>R2C2</td> <td>R2C3</td> </tr> <tr> <td>R3C2</td> <td>R3C3</td> </tr> </table> The rowspan=&quot;3&quot; in the <td> element accomplishes the same thing, but stretches a cell across multiple rows instead. R1C3 R1C2 Span 3 Rows R3C2 R2C2 R3C3 R2C3