Guidelines and Guide Objects Overview
When you are drawing objects in a document, you can use guides to ensure that what you draw appears in exactly the correct position. There are two types of guide - guidelines and guide objects.
Guidelines
Guidelines are vertical and horizontal dotted lines that are displayed on the screen. You can move them by dragging them. If you enable Snap to Guides, any objects or handles you drag near the guideline will lock onto it. Guidelines exist in the guides layer. This layer is just like a regular layer in a document and can be locked and disabled.
For more information, see the following pages:
Listing the positions of guidelines
Guide Objects
Guide objects are normal objects except they live in the guides layer. If you enable Snap to Guides and drag an object or handle near a guide object, it will lock onto it. All objects in the guides layer are shown as dotted outlines. For information on creating guide objects, see Moving objects to the guides layer.
Tips
If you want to draw a perspective drawing, go to the guides layer and draw a set of straight lines radiating out from a vanishing point. If you now move to a regular layer and use guide snapping, you can easily create objects using the perspective guides.
Normally the guides layer is a background layer and guides appear behind other objects. If you want guides to appear on top of other objects, move the guides layer forward - see Reordering layers for details.