Although there were three in number, these minor goddesses were a collective incarnation of grace and beauty and always referred to as one.
There was Aglaia (Splendor), Euphrosyne (Mirth) and Thalia (Good Cheer). Supposedly they were the daughters by Zeus and a Titan named Eurynome. Along with the Muses, these girls were the epitome of song, and no banquet without them was fulfilled.
The Charities/Graces also have artistic significance; famous works such as Primavera by Botticelli or works by Raphael depict encircled Graces.