Tables are great in the right time and place but use them carefully. Tables are great for presenting structured data but are also used to achieve advanced layouts.
Using tables to get a fancy layout can backfire if people are using Assistive Technologies or have cognitive disabilities. Screen readers will move linearly through the content from left to right one row at a time. Merged cells and nested tables can impair a user’s ability to understand the material.
Tables will be read to someone using a screen reader from right to left which can often make it hard for someone to interpret the data contained within them. When the information in your table is pertinent to your message and does not make sense or is hard to understand when each cell is read from right to left consider adding a caption and a summary.
When a screen reader comes across a summary tag for a table it will read the summary text out first before it starts to read the contents of the table. A user can then decide, based on your summary, whether or not they need to hear the remainder of the text or if they can skip to the next section of your content.