Illustrator has another type of guide called a Smart Guide. Instead of being just a static object to which you can align something, smart guides are dynamic and provide useful feedback as you draw. There are six different types of Smart Guides you can set up in the Preferences dialog box (4.6). You can enable as many of these guides as you’d like, or disable them altogether. You may find it a little intrusive to have these guides on all the time; you can toggle the guides on or off by choosing View > Smart Guides (U/Ctrl+U).
4.6. Setting up smart guides in the Preferences dialog box
What follows is a description of how each type of Smart Guide works. Play around with each of the settings to see which ones work best for your workflow.
Alignment guides help you to align objects while drawing, moving, or editing. They help you align objects and anchor points to the centers and/or edges of nearby objects (4.7) without having to pull guides from the ruler.
4.7. Using alignment guides helps align objects as you move them around.
Anchor/path labels appear as you hover over an object to let you know whether you have an anchor point, path, center point, or edge of an object under your cursor. This really aids in making selections once you have a more complex design (4.8).
4.8. Anchor/path labels let you know what’s beneath your cursor.
With the Object Highlighting Smart Guide enabled, objects are highlighted with a selection outline as you hover over them. Again, this Smart Guide is most useful when you have a lot of objects on the artboard, as it allows you a preview of what object will be selected when you click. It also allows you to see objects that have live effects applied, as seen in 4.9.
4.9. Object highlighting shows which object will be selected when you click. It also shows the original shape of objects with effects applied to them.
Measurement labels display the size, distance, and position of objects as you draw, move, or edit them (4.10). It helps you to be really precise with layout and placement in context.
4.10. Measurement labels provide in-context information about the dimensions and position of objects.
Transform tools display guides when used with the Rotate, Scale, or Shear tools (4.11). These guides help to constrain these transformations to common angles when drawing, so you don’t have to use the Shift key to do the same thing.
4.11. In this example, the guides help you snap an object’s rotation to 45-degree angles.
When drawing with the Pen tool, construction guides help to constrain line segments to specified angles (4.12). You can choose a preset angle group or specify your own custom angles (see 4.6).
4.12. Construction guides make drawing with the Pen tool a little easier.