Ruler and Guides
Rulers can be used to align and/or evenly distribute images in the design. Although inch is used as the default measurement unit, you may choose the unit of measurement (inch, pixel, mm or %). You may also change the initial origin point of the rulers.
To turn Rulers on, go to Document > Show Rulers or use a shortcut key, Cmd + R for Mac or Ctrl + R for PC. Although inch is used as the default measurement unit, you may choose the unit of measurement (inch, pixel, mm or %) by going to Document > Ruler Units or right-clicking on the ruler. In addition, you may change the initial origin point in the design area by dragging the initial origin point in the upper left hand corner of the design area into the design area. While moving the origin, you will see the ruler move along with the movement of the mouse.
To turn Guides on, go to Document > Show Guides or use a shortcut key, Cmd + : for Mac or Ctrl + : for PC. You can then drag from the Ruler and drop a Guide into the design area. Ruler must be turned on as well to be able to add Guides.
Guides can be very useful in aligning images, text and shapes in a design. Objects will snap to the guides if the option is selected (Document > Snap to Guides).
Guides can easily be moved by drag and drop or right-click to select a location. To remove/delete a guide you may drag a Guide back into the Ruler or right-click and select 'Delete.'