Data tables are structured by placing information in row, column format -- similar to a spreadsheet. Assistive technologies, such as screen readers attempt to interpret this information in a meaningful way. Screen readers, in particular, read text linearly; that is, they read across the line from left to right. That causes a problem when attempting to render tables meaningfully. To solve this problem for simple data tables, table rows (<TD>) and table headers (<TH>) must be explicitly identified within HTML code.