Tallow is hard fat from animals — usually cattle or sheep — that has been melted down and cleaned so that it sets into a firm, pale, waxy block. Before cheap electric light, this was how ordinary people made candles: you dipped a string again and again into melted tallow until the layers built up. Tallow candles were the poor person's candle. They were cheap, but they smoked, they dripped, and they smelled of old meat; rich houses burned beeswax candles instead, which cost far more and smelled sweet. Tallow was also used for soap, for greasing wheels and machines, and for treating leather to keep out water. It is mostly an old word now, tied to history lessons, museums and old novels — you would not use it about the fat in your kitchen. But it has come back a little in two places: some people making handmade soap and skin creams use tallow on purpose, and some cooks and restaurants say 'beef tallow' when they mean beef fat used for frying. There is also a verb 'to tallow', meaning to rub or cover something with tallow, but it is rare and old. One useful distinction: 'tallow' is hard fat that has been rendered — melted and strained. 'Lard' is the same kind of thing but from pigs. 'Suet' is the raw, hard fat around an animal's kidneys, before you melt it.