Layout table without and with role="presentation"

Hover over the tables below to show the borders.

Layout table

Basic example of a layout table. Visually it may look fine, but in assistive technologies it's announced as, well, a table, with all the extra information (rows, columns, etc).

Layout table remediation

Basic example of a layout table. This time, the "table-ness" has been suppressed by using role="presentation"

Some browsers, like Firefox, and assistive technologies, like JAWS, use heuristics to determine if a table is likely to be a layout, rather than data, table and expose the role accordingly.