To merge cells, set colspan and rowspan attributes on <td>
elements:
<table>
<tr>
<td colspan="2">Foo</td>
</tr>
<tr>
<td rowspan="2">Bar</td>
<td>Baz</td>
</tr>
<tr>
<td>foobar</td>
</tr>
</table>
This results in:

To merge cells, set colspan and rowspan attributes on <td>
elements:
<table>
<tr>
<td colspan="2">Foo</td>
</tr>
<tr>
<td rowspan="2">Bar</td>
<td>Baz</td>
</tr>
<tr>
<td>foobar</td>
</tr>
</table>
This results in: