In Tuscany it's is a sausage made primarily from leftover pork cuttings -- cartilage, snippets of meat, and so on, which are stuffed into the skin of the animal, or a burlap bag, and cooked. Therefore, in appearance it somewhat resembles a porchetta, the roast pork done whole over a spit. However, the taste is quite different and rather particular; people generally make sure their guests like it before offering it.
A general overview of salumi, Italian cold cuts.
Affettati Misti, a mixed cold cut antipasto