They are usually made from salt pork or fatback with the skin on.
They are used as both an ingredient in dishes, and as a garnish, to add both flavour and texture. They can be sprinkled on braised collard greens, crumbled into the batter for corn bread, or just eaten by themselves as a snack.
Corn bread with cracklings in it is called “cracklin bread.”
In Provence, France, a bread called “Fougasse aux gratillons” is made with pork cracklings.
Wash the pork fat and pat dry. Trim the fat to be 3/4 cm (1/3 inch) thick, and score without going all the way through.
Rub salt into the fat, let stand for an hour, and pat dry again to sop up excess moisture that the salt has drawn out.
Cut into strips, following the scores you made, and put in a baking dish. Pour some water into the dish, taking care not to get any water on the top of the strips.
Bake in oven at 230 C (450 F) until golden-brown and crisp — this should take around 1/2 hour.
You can make them ahead, and then reheat for 10 minutes before serving. Best re-heated in some kind of oven as opposed to microwave, if possible, to maintain crispness.
In the American south, referred to as “cracklins.”