The Grid Guide is a screen pattern in the background of the Work Window. (It is never visible in your published project.) It offers a visual reference for placing objects on the page and helps you align them vertically and horizontally. (See Work Window.)
The default size of each box in the Grid Guide is 10 square pixels. However, you may change this setting in the Guide/Display Options dialog box. (For more information, see Guide/Display Options Dialog Box.)
You can toggle the Grid Guide off or on by selecting View>Display Grid Guide, or by pressing the CTRL+G keyboard shortcut. Or, you can select/deselect the Display Grid Guide option box on the Guide/Display Options dialog box. (For more information, see Guide/Display Options Dialog Box.)
You can also use the Snap Grid function to help align objects by restricting their movement to specified incremental values in the Grid Guide. For more information, see Snap Grid.