Using colspan in Tables

A B
C  
     

Using rowspan in Tables

A B
C
   

Note that there are 5 cells in the table - and therefore only 5 td (or th) elements in the table.

Using both in 1 cell??

A B C  
One Two  
         

Note that there are 3 rows and 5 columns for 15 cells in the table before "spanning". Cell B spans 4 cells - so we are left with 12 cells.