In page layout, rules are lines used to separate, organize, emphasize, or otherwise decorate a page. Downrules refer specifically to vertical rules placed between columns of text, used to provide greater visual separation between the columns.
Place downrules between columns of text to keep the readers eye from jumping the alley (space between columns) and becoming confused. Use narrow downrules, especially in narrow spaces to avoid visually overpowering the page and running into adjacent text.
Also Known As: vertical rules | lines | column dividers