Costume

Costumes are decorative items that are equipped into a character's costume slots to change their appearance. They are worn over a character's existing armor, and do not affect any stats.

Costume slots
Costume slots are located in your Inventory window, under the cape and weapon slots, making it possible to wear a festival hat and/or a costume, at the same time with your armor. Festive hats in your inventory prior to the December 17th, 2009 update will still replace your headgear, and not make use of the Costume Headpiece slot. Costume slots can only hold a costume, and/or a festival hat.

Acquisition

 * Costumes are available from the Guild Wars In-Game Store; once purchased, you acquire them from Costume makers.
 * Festival hats are available at many Special events. Previously acquired festival hats are acquired from Festival hat makers.

Properties
All costumes share the same general properties, most notably that they are purely cosmetic: even though they have the appearance of armor, they will never offer any in-game advantages:
 * Costumes will never have an armor rating. They cannot be upgraded, using runes or insignias.
 * They cannot be salvaged for materials.
 * They cannot be displayed during PvP combat.
 * They can be dyed.
 * Once they are purchased, they are available to all characters on the same account; there are no additional in-game costs.

Trivia

 * The two costume inventory slots were added in the 17 December 2009 game update, when existing festival hats were converted to costume headpieces from armor.
 * The March 10th, 2011 update fixed a bug that caused the character selection screen to display costumes with the wrong colors.