By default, the ToolTip property is "..." ( three dots ). Use the ToolTip property to assign a tooltip to a column. If the ToolTip property is "...", the control displays the column's caption if it doesn't fit the column's header. Use the Caption or HTMLCaption property to specify the caption of the column. The column's tooltip shows up when the cursor hovers the column's header. Use the CellToolTip property to assign a tooltip to a cell.  The control  fires the ToolTip event when the column's tooltip is about to be displayed. The ToolTipWidth property specifies a value that indicates the width of the tooltip window, in pixels.