A sausage casing is the material that contains and encloses the filling
of the sausage. The casing determines the sausage size and shape.
Natural animal intestines were first used for sausage casings, and then,
with the technology advances of the 20th century, artificial casings were
developed from regenerated collagen and cellulose.
advances have also produced plastic casings made from polyamide
materials in single and multi layer varieties.