What are smart guides and how do you use them?

What will be an ideal response?

Smart guidesare guides that appear automatically as you position objects on a page. Smart guides are visual clues that let you know when the object you are positioning is touching a side or the center of another object, a margin guide, or the center of the page. To use smart guides, you need to select the Smart Guides command. You can change the color of smart guides in the Guides & Pasteboard section of the Preferences dialog box.