Use Guides and Snapping in InDesign CS5
When you’re creating page layouts in InDesign Creative Suite 5, using guides with snapping enabled helps you align elements on a page and position objects in the layout. Aligning objects by eyeballing them is difficult because you often can’t tell whether an object is out of alignment by a small amount unless you zoom in to a large percentage.
Make sure that snapping is enabled by choosing View→Grids and Guides→ Snap to Guides. When you drag the object close to the grid, the object attaches to the guideline like it’s a magnet. Aligning an object to a guide is easy after you create a guide, and you’ll notice that InDesign displays temporary guides when you move an object near another object or near a guide.
Column guides: Evenly distribute a page into columns and can be used to align text frames in a document. These guides are set when you open a new document in InDesign that contains more than one column. Column guides evenly distribute the page into columns and can be used to align text frames in a document.
Margin guides: Define the area between the edge of the page and the main printable area.
Ruler guides: Manually defined and can be used to align graphics, measure objects, or specify the location of a particular asset you want to lay out.
Smart guides: As previously mentioned, smart guides offer the ability to align objects on an InDesign page to other objects or even to the page. Smart Object alignment allows for easy snapping to page item centers or edges or page centers. In addition to snapping, Smart Guides give feedback to the user indicating the object to which you are snapping.
Don’t forget that in InDesign CS5 you delete all guides at once by right-clicking the ruler (Windows) or Control-clicking the ruler (Mac) and selecting Delete All Guides from the contextual menu.