Rulers and Grids help in aligning, positioning and sizing objects placed on a layout.
When you click the rulers, it displays a horizontal and vertical ruler along the edges of a layout. Each ruler consists of guide-lines that track the position of the pointer as you move it on the layout.
When you choose the grid, it displays a series of nonprinting intersecting horizontal and vertical lines on a layout, which you can use for creating, resizing, positioning, and aligning objects. Gridlines adjust when you change the unit of measure.
Now, a grid and a ruler become interrelated when you decide to change the unit of measure. You can follow any one of the following to change it -
Right-click on a ruler, and choose a unit of measure from the shortcut menu.
Click the upper-left corner of the document where the horizontal and vertical rulers meet until you see the desired unit of measure.
In the Inspector, click the unit of measure, which appears next to many options, until you see the one you’re looking for.