Pork belly is the flesh from the belly area of the pig. When sliced and cured, it becomes bacon. Left whole or cut into smaller chunks, pork belly responds well to moist heat cooking, turning it fork-tender.
When the skin is removed, it's salted, cured, and smoked to make bacon. (If it's salted and cured but not smoked, it's pancetta.) Pork bellies are more traditionally seen in the cuisines of northern Europe and Asia.