Leather:

Leather is a material created through the tanning of hides and skins of animals, primarily cattle hide. The tanning process converts the putrescible skin into a durable, long-lasting and versatile natural material for various uses.
Together with wood leather formed the basis of much ancient technology the leather industry and the fur industry are distinct industries that are differentiated by the importance of their raw materials. In the leather industry the raw materials are by-products of the meat industry, with the meat having higher value than the skin.
The fur industry uses raw materials that are higher in value than the meat and hence the meat is classified as a by-product. There are a number of processes whereby the skin of an animal can be formed into a supple, strong material commonly called leather. Vegetable-tanned leather is tanned using tannin (hence the name "tanning") and other ingredients found in vegetable matter, tree bark, and other such sources.
It is supple and brown in color, with the exact shade depending on the mix of chemicals and the color of the skin. It is the only form of leather suitable for use in leather carving or stamping. Vegetable-tanned leather is not stable in water; it tends to discolor, and if left to soak and then dry it will shrink and become less supple and harder. In hot water, it will shrink drastically and partly gelatinize, becoming rigid and eventually brittle