It typically has a yellowish-brown outer pellicle which is a result of this curing process.
Its purpose is to preserve these protein-rich foods, which would otherwise spoil quickly, for long periods.
There are two mechanisms for this preservation: dehydration and the antibacterial properties of absorbed smoke.
In modern days, the enhanced flavor of smoked foods makes them a delicacy in many cultures.
Typically, a sausage is formed in a casing traditionally made from intestine, but sometimes synthetic.