Grid lines are vertical or horizontal lines that can be displayed on charts to help you compare the charted data with the values along the horizontal and vertical axes of the chart.
For basic chart customization instructions, see Basic Customization Instructions.
To hide or show grid lines:
Choose a setting from the Gridlines drop-down list to show only horizontal grid lines (Horizontal), only vertical grid lines (Vertical), both horizontal and vertical grid lines (Both), or choose None to hide both horizontal and vertical grid lines.
When all the settings are complete, click OK.
The chart is displayed with the new settings.
You can press Ctrl+l to toggle the horizontal grid lines on and off.