The cup was a creation of Helga Hufflepuff, the celebrated founder of Hufflepuff House. 
The Hufflepuff Cup was said to possess many magical powers, though the exact nature of those powers is not known. Hufflepuff was brilliant with food-related charms and with house-elves, so the cup may have been the very first dining utensils at Hogwarts to assist in the magical transportation of food from teh House-Elf Kitchens. The cup also has the dubious distinction of being the only object known to have been stolen from a vault at Gringotts Wizarding Bank.
 
5 inches in height
Cannot be used as drinkware