In this sense, leather is collected by skinningbeasts. These items can usually be used directly by the Leatherworking profession without prior processing or treatment. The type of leather is usually directly related to the level of animal being skinned.
Leatherworkers can also combine lighter leathers into heavier ones, even combining ruined leather scraps into usable leathers.
Leather is closely related to Hides, although Hides are rarer and must often be prepared for use.
Basic Leather
There are 11 basic leathers:
NB: It seems the lowest level mob which can be skinned may now be level 5. This needs verification, though experience shows it may be true.
The Ruined Leather Scraps which you get when skinning low level mobs are vendor sell items unless you also have Leatherworking, in which case 3 of them can be made into light leather. The frequency of getting these drops off rapidly around 10th level mobs and you will not see anymore of them at all once you are skinning 17th level and above mobs. Note: As of Patch 3.0.3 you do not need the Leatherworking skill to convert 5x Borean Leather Scraps to 1x Borean Leather.
Leather Conversion
Leatherworkers can assemble low-level leathers into higher-level leather.