Whichever type of hide you choose, you need to also understand the tanning process, and how it adds or detracts from the quality of the leather. Leather was once the skin of an animal, and therefore must go through a tanning process to strengthen it, and to keep it from decomposing. Tanning makes the skin stable and rot proof without sacrificing its structure and strength. The tanning process involves several stages, including the removal of the hair and the outer layer of skin, as well as the fatty part of the flesh. The hide is then stabilized by one of several methods using animal oils, alum, chrome salts or vegetable tanning. How it is actually finished determines the quality, or riding grade, for our purposes.