What is tallow?

Tallow is essentially cow or sheep fat, processed from suet. It is a hard solid at room temperature. Unlike suet (the fatty matter that protects the animal's kidneys), tallow can be stored for a long time without being refridgerated to prevent decomposition, as long as it is kept in an airtight container to prevent oxidation.

Rendered (melted) fat obtained from pigs is known as lard.