RowSpan and ColSpan can be used in HTML design if merging of columns or rows is needed within a table.
RowSpan can easily implemented in ASP.NET GridView or DataGrid web controls. In this Wiki article you will find a sample of how RowSpan can be used with GridView's RowCreated event.
Here is sample code :
' Control the row type, continue if it is a DataRow
If e.Row.RowType = DataControlRowType.DataRow Then
' If it is the first row add a new cell
If e.Row.RowIndex = 0 Then
Dim tc As New TableCell()
tc.RowSpan = 1
' In the following rows alter the RowSpan property of the recently added cell by one
Dim tc As TableCell = GridView1.Rows(0).Cells(GridView1.Rows(0).Cells.Count - 1)
tc.RowSpan = tc.RowSpan + 1