The main use of Tailoring is for Control Wizard's armour, as they only wear cloth armour; whereas the other classes (so far) wear chainmail like armour.
Currently there are 20 levels of Tailoring, which are needed to make increasingly high level items. Level 20 is required for any of the known Level 60 Very Rare (purple) items.
Tailoring recipes are listed here: Tailoring Recipes
Tailoring Return to Professions page here: Professions