Gelatine does not occur "free" in nature. It has to be made or manufactured. However, it is a natural ingredient, in that it derived from natural ingredients and has no additives. Nowadays, it is made mainly from beef bones and hides and pork skin, which contain protein collagen, the essential ingredient required for the production of gelatine.
It is a lengthy process in which extraneous substances, such as minerals, fats and albuminoids are removed by chemical and physical treatment to give a purified collagen. It involves several cleansing and purification steps and is finally dried in an air chamber, then processed into the end product (sheets, granules, powder)