Tailor

Tailors are merchants who upgrade Ezio's pouches, allowing him to carry more Medicine, Poison and Throwing Knives. They can also dye Ezio's armor with various colors. However, dyeing has no real function on gameplay.

Pouch
Upgrading your Pouches increases Ezio's carrying capacity of a certain item by 5. It is required to upgrade to a lower priced upgrade in order to access the higher priced ones, this however, is not true for the Medicine Pouch. You can purchase the Large Pouch for 6,000 and have your capacity upgraded to 15 without purchasing the Medium Pouch for 3,000, good way to save some coin.

Dye Clothes
Dye Colors available change depending on what region the Tailor is located in. You can get an achievement "Perfect Harmony" by dying Ezio's clothes with Wetland Ebony and Wetland Ivory.