Tin is a mineral added in the Nature Update. It was added along with some other minerals, which include Brass and Copper. Tin Ingots must be crafted into required items, which is smelted from Tin Ore mined out of the ground.
Tin Ingots can be used to make armor and tools as strong as iron. It can also be made into a tin can. Tin Cans can be made into many foods, including canned veggies and spaghetti. It can also make tin foil, which you can wrap food in to prevent them from spoiling.