Accordions are a UI pattern where you click on a title (in a vertical stack of titles) and a panel of content reveals itself below. Typically, all other open panels close when the new one opens. They are a clever and engaging mechanism for packing a lot of information in a small space.
One way to look at an accordion is like a collapsed single column of a table. I was recently building a page for a client site, where the information that they provided really made sense to present as a table. But it was too much information to view all at once. I thought it would have been overwhelming visually. I also thought that it was most likely that people visiting this page would know what they needed right away, so having them click once to get it seemed pretty reasonable. So, a table of accordions!
Another consideration in this table I was building is that there was enough columns that each individual column (should they have been equal width in the space available) wasn’t very wide, maybe 150px. Some of these cells contained several paragraphs of text. A cell 150px wide with several paragraphs of text would awkwardly tall. Hence, the Grid Accordion is born!
The Grid Accordion works with the same theory as most other accordions. Only one cell is open at a time. The big thing is that the column of the current open cell expands to a reasonable reading width.