Adding Borders to Cells
The light gray grid that appears on the worksheet helps your eyes move from cell to cell. Although you can print these gridlines, sometimes a different grid pattern better emphasizes your data. For example, you might put a decorative line border around the title, a double-line bottom border below cells with totals, or a thick border between sections of a complicated worksheet. You can add borders of varying colors and widths to any or all sides of a single cell or range.
Apply a Border
Apply a Border Using the Formatting Toolbar