Some of the preconfigured chart layouts in Excel include gridlines, and some do not. You can add or remove gridlines by selecting the chart, clicking the Layout tab under Chart Tools, and clicking Gridlines in the Axes group. In the submenus that appear you’ll see the terms major gridlines and minor gridlines. Major gridlines emerge from axis subdivisions called major tick marks. Minor gridlines are drawn from further subdivisions known as minor tick marks. Excel determines the positions of these tick marks automatically, but you can override its decisions if your labels or gridlines are not spaced to your satisfaction. (See Adjusting the Spacing Between Gridlines on page 710.)

Be aware that major gridlines in certain kinds of three-dimensional charts can make data points appear to have less than their true value. In the following illustration, for example, the data points have exact integer values from 1 to 10, but the gridlines, in combination with the three-dimensional perspective, make each point appear somewhat smaller:

To avoid confusing the viewer in this kind of chart, you might want to add data labels.