There are many different types of tafetta. Most are made of a fine, plain weave, usually smooth, crisp and lustrous. Faille (pronouced sort of like 'file') has a softer feel to it with a ribbed weave. When you see an iridescent effect to your dress, the fabric is called a changeable taffeta - warp and weft are different colors.
Taffeta is originally a Persian fabric known as Taftan. Mostly reserved for dresses and gowns, their cleaning can prove tricky. Never wash tafetta in water, always use a dry cleaner. It is known for color runs, and can be very difficult to press if wrinkled in water.
However, the look of taffeta can not be denied!