Leather

Leather is an animal skin used to make armor and books.

Drops from animals
Cows, mooshrooms, horses, donkeys, mules, llamas, and hoglins drop 0–2 leather upon death. The maximum amount is increased by 1 per level of Looting, for a maximum of 5 leather with Looting III.

Foxes that are holding leather also have an 8.5%‌ or 100%‌ chance to drop the leather they are holding upon death. Alternatively, a player can drop a food item, causing the fox to drop the leather.

Fishing
Leather can be obtained as a "junk" item from fishing.

Bartering
Piglins may barter 4–10 leather when given a gold ingot.

Trading
Novice-level leatherworker villagers have a $2/3$ chance to buy 6 leather for one emerald in Java Edition, and always offer the trade in Bedrock Edition.

Repairing
Leather is the repair item for the leather armor material, and thus can be used to repair the following items in an anvil:

Issues
Kůže Leder Cuero Cuir Bőr Cuoio 革 가죽 Leer Skóra Couro Кожа 皮革