Page margins allow you to design with printing in mind. Margins (hidden by default) are indicated by a blue solid line, but this colour can be changed.
The margins give an indication of the extent of the page that will be printed when using a desktop printer. Design elements positioned outside the margins may not be printed.
Margin positions are set up on document creation either manually or by using the settings of an installed printer. They are non-printing and non-exporting.