A specialty of the central Italian regions of Umbria and Lazio, guanciale is pork jowl or pig cheek that's been cured with black pepper, red pepper, or spices. It's softer in texture and less salty than pancetta, but possesses a stronger, fattier taste.
Guanciale's rarely eaten raw; rather, it's well-suited for sautéeing with vegetables, enriching a stew, or boosting the flavor of meat. It's an essential ingredient in several classic Roman pastas, such as spaghetti alla carbonara and bucatini all'amatriciana.
Source: Flickr User thebittenword.com