The cooking fat made by slowly cooking and straining pork fat is lard.
Lard is produced by rendering fatty tissue from a pig. In dry rendering, pieces of fat are heated in a pan or oven until the fat melts, then the liquid is strained from the remaining solids. Wet rendering uses water, steaming, or boiling; because fat does not mix with water, the rendered fat can be separated as it cools or rises to the surface.
The source of the pork fat affects the result. Leaf lard, taken from fat around the kidneys, has a mild flavor and is prized for pastry. Fatback produces a more distinctly pork-flavored cooking fat. Lard is often confused with tallow, which comes mainly from cattle or sheep, and schmaltz, which usually means rendered chicken or goose fat. Cracklings are the browned solids left after rendering.