Tallow is a form of rendered fat, classically made from beef, although technically any animal could be used as a source. Vegetarian versions made from plants such as the tallow tree are also available, although the composition of plant-based fats is slightly different from the traditional form. There are a number of uses for tallow, making it a product in consistent demand.
Typically, tallow starts with the extraction of suet from a carcass. Suet is hard fat found in the neighborhood of the kidneys and around some other organs. While suet can be used as-is, rendering it removes the impurities and also extends the shelf life. Once suet is rendered, it becomes tallow. As long as it is stored in an airtight container in a cool environment, it can keep for an extended period of time, unlike suet, which will become rancid.
Beef, pig, and mutton tallow are all fairly common. It is also rendered from animals like horses. The product is high in monounsaturated fatty acids, with lesser amounts of saturated fatty acids and polyunsaturated fatty acids. The composition of the fats causes it to be solid and white at room temperature, and properly rendered tallow is odorless and tasteless.
Historically, tallow has been used as a fuel, a base for candles, a treatment for leather, and a base for soaps. In the modern era, it is used commonly as a lubricant and cooking oil. It can also be turned into a biofuel, used as a feed supplement for various animals, and included in leather dressings and waterproofing compounds designed for leather. Some industries have turned away from animal fat in favor of plant-based materials, under the belief that these materials are easier to handle and clean up.
In some regions, it is possible to purchase plain tallow for various projects, especially if you live in an area with a rendering plant. In other cases, consumers only interact with it indirectly. It is also possible to make tallow at home, although the process can be quite smelly and messy. In order to make this type of rendered fat, you need access to suet and sturdy pans to cook it in. It is made by cooking diced fat in water, cooling it, straining it to remove impurities, and skimming off the top layer of fat which accumulates after a night of chilling. This process is repeated to make the fat as pure as possible.