Select the cells you want to border
Go to the Home tab
Click the Borders drop-down in the Font group
Choose a border option such as All Borders, Outside Borders, or Thick Box Border
For more options, click More Borders
In the Format Cells window, select the Border tab
Choose the line style and border color
Click the border positions you want to apply
Click OK
Use the Draw Border tool from the Borders menu if you want to draw borders manually
Use keyboard shortcut Ctrl + Shift + 7 to apply an outline border on Windows
On Mac, use Command + Option + 0 for an outline border
Remove borders by selecting the cells and choosing No Border from the Borders menu