Dadoes are grooves cut in boards across the grain. They are also cut in plywood and other sheet goods to accept another piece of plywood, as a shelf being let into the side of a cabinet. And they add strength to the cabinet. All pluses.
But they do have one drawback: chipout along edges of the dado. This doesn't matter much if the dado doesn't show in the finished project, but if you're using some expensive hardwood plywood, this can be really frustrating, and worse.
Digging around in the video archives at ShopNotes magazine, I came across this video from a couple years ago, showing seven techniques to avoid chipout when cutting dadoes on a table saw.
If you're not familiar with ShopNotes magazine, do yourself a favor and get a preview issue. Also, check out Woodsmith's Table Saw: Tough Cuts Made Easy softcover book for lots more table saw techniques.