There are two types of tables: layout and data. Layout tables position items on a page; data tables present data in a grid. A data table must have a header row and include a caption or table summary. Simpler is better.
Tables in Documents
After you design your table, you will need to take a few additional formatting steps to make it accessible for adaptive technology users, that is, you’re marking up the document to give the screen reader software cues about what information is contained in the rows and columns.
In whatever application and version you’re using, look for a setting in the table properties panel that lets you indicate the header row, that is, the row that indicates what information is located in each column. In Microsoft Word, the method is to check the box that says “repeat as header row at the top of each page”. While the option doesn’t sound like it, it actually does the trick that makes the table work with screen readers.
However, it isn’t possible to indicate column headers in Microsoft Word, so if your table includes categories contained in rows, your table might be confusing to someone using a screen reader.
When you include a table in a document, you should also include a table summary that describes the content contained in the table, e.g., “Lessons, assignments and grade points available this semester.”
In Microsoft Word it’s possible to hide the table summary from the visible area of the document. You can place the table summary in the table properties panel, under the Alt Text tab. The alt text tab has two fields, one for the title of the table and one for the description, as shown in this screenshot:
Complete both the title and description fields for all tables. The title of this table is “Language Test Information Sessions” and its description is “Date, time and location of language test information sessions for fall semester 2016.”
You can use the alt text for tables any time. However, if you display the table summary on the visible page, all users will benefit from being able to see it.
In general, you should only use tables to display data, rather than as a means of page layout. (To control page layout in documents, you should learn to use the word wrapping and padding features.)
Tables in PowerPoint
While it’s possible to visually format a row in PowerPoint so that looks like it has header rows (e.g., make the top row of cells bold and with darker background fill), there’s not a way to mark it up for screen reader software to be able to identify the header rows. For this reason, Webaim recommends to share the PowerPoint file as a PDF and to tag the PDF with table tags in Adobe Acrobat.
Tables in PDFs
Properly structure your table in the editing software (Microsoft Word or other), save it as a PDF, then open it in Adobe Acrobat to tag the PDF for accessibility.