Rowspan: Combine Cells vertically
Colspan: Combine Cells horizontally
Example
<table border = '1'>
</tr>
<tr>
<td>Row-1 Column-1</td>
<td colspan="2">Row-1 Column-2 and 3</td>
<td rowspan="2'>Row-1and2 Column-4</td>
</tr>
<tr>
<td>Row-2 Column-1</td>
<td>Row-2 Column-2</td>
<td>Row-2 Column-3</td>
</tr>
</table>