White space is the least distracting means of visually separating columns and rows. In other words, lines may not be needed – your eye automatically sees the structure, without the need to add any distracting and superfluous elements. This allows the eye to concentrate on the data and browse easily from item to item.

Garish, high-contrast ‘zebra’ striping of tables and heavy gridlines are more likely to deter readers than improve ease of reading. Therefore, rules (gridlines), shading and other dividers or guides should be minimised. Vertical rules at the edges of a table to separate the first or final column from adjacent empty space are unnecessary.

However, if your table is very large or complex, so that some data cells are a distance from the table headers, consider using subtle lines or shading to help guide the eye. In these cases, dividers or guides should run in only 1 direction, either dividing rows or dividing columns, not both (this would form a grid). The guides should run in the most logical direction to link cell data in the appropriate related information string, generally horizontally.

If your table is structured bidirectionally, the guides should run horizontally, because this is the predominant reading direction.

Rather than applying rules or shading to the entire body of a table, consider using these features to group or highlight subsets of data, such as summary rows. If alternate shading of rows is necessary, keep the shading subtle (pale) and low contrast (eg white alternating with a 10% tint of your chosen colour). Text can also be emphasised or highlighted by applying bold or italics to selected cells, such as totals; keep all body text in a single colour.

Although spacing is often enough to visually group or separate data, do not insert blank rows or columns to achieve that spacing – instead, use cell margins and good formatting to ensure sufficient space between data.