A taco shell is a crispy circular corn (maize) tortilla that is folded to form an envelope which can be filled with meats, salads and sauces.
The folded type of taco shell normally breaks and spills its contents on first bite. However, I've recently discovered (sic) a variation on the folded type, pictured above. It's a neat mouth sized tray! Brilliance! Our local Morrisons stock them, though I don't know about other supermarkets.
Use them in our minced beef for tacos recipe.