To merge several cells into one, you need to create a spanning
cell
A spanning cell is a cell that occupies more than one row or column in a table
Spanning cells are created by inserting the rowspan and colspan
attribute in a <td> or <th> tag.
The syntax for these attributes is:
<td rowspan=value colspan=value>
</td>
value
is the number of rows or columns that the cell spans in the table