There are different View Preferences you can choose to have displayed when designing your pages. They can easily be turned on and off at any time.
Preview Mode: Preview mode allows you to view your page without any of the guidelines. It also previews your page without the bleed, so you can see exactly where the book will be trimmed.
Show Ruler: This mode allows you to see a ruler on the outline of your page. This allows you to have an accurate measure of elements on your page.
Snap to Objects: This mode allows you to easily align elements on your page. When you have a photo or text box selected, it will snap into other elements on your page so that they are perfectly lined up.
Snap to Grid: This preview mode shows a grid on your page so that you can see exactly where everything lines up. It also allows you to snap objects to the grid lines so that you can align objects exactly where you want them.