You use 'colspan' on a <td> to set the number of columns in your table that you want the <td> to occupy. This is typically used when there will be rows in your <table> that will have a different number of columns. For example:
It's a matter of controlling the appearance of the table. If your rows have different numbers of columns and you don't use colspan anywhere, the browser will decide for itself which <td> to expand to the full width of the table.
Table cells can span across more than one column or row. The attributes COLSPAN ("how many across") and ROWSPAN ("how many down") indicate how many columns or rows a cell should take up.
For example, we might want to create header cells for each department in our table of names and phone numbers. In this table, the header cells in the first and fifth rows span across two columns to indicate the department for each group of names.
A milling machine is a machine tool used to machine solid materials. Milling machines are often classed in two basic forms, horizontal and vertical, which refer to the orientation of the main spindle. Both types range in size from small, bench-mounted devices to room-sized machines. Liquid Filling Machine