Guides are lines that you drag onto the document from the rulers. They help
you place and align objects more precisely. You can also use guides to measure
the size of page elements, or emulate the folds (visible
areas) of web browsers.
help you align elements
To help you align elements, you can snap elements to guides, and snap guides to
elements. (Elements must be absolutely positioned in order for the snap feature
to work.) You can also lock guides to prevent them from being accidentally moved
by another user.
