Beef suet is the raw, hard fat of beef that is obtained from the loins and kidney area. It has a high smoke point (392 degrees) that makes it ideal for deep frying and pastries, so is rendered frequently for these uses. The melting point is between 113-122 degrees.
Once rendered (simmered to remove water content through evaporation) and filtered, it is known as tallow.
Many people use rendered suet mixed with bird seed in their bird feeders as feed cakes!