Leatherworkers specialize in creating leather and mail armor, as well as items such as armor kits, capes and quivers. At level 60, many items from Leatherworking are used in PvE situations, as they offer resistance stats. Leatherworking is the best combined with Skinning, and I highly recommend to level these professions together. It will be a lot easier to get the needed leathers if you have Skinning.