Tables should only be used for tabular data or in rare cases where a desired layout effect cannot be acheived without. The problem is that assistive devices read table data from left to right, row by row. Therefore, table column headers are not repeated for each row or cell, making the audible version of the table unintelligible.

If a table layout must be used for text formatting (not tabular data) one must include a summary tag to properly identify it as such. For example, if a table is used for layout purposes only the following tags should be included in the html at the head of the table: <table summary="for layout only"> or <table summary="format">

The desired effect of this is to identify the purpose of the table to the screen reader which will read it as it would text.


Web AIM's Creating Accessible Tables.