The house-elves at Hogwarts amongst other duties provide all food to students and staff. They cook a wide variety of dishes especially at the feasts.
The various dishes are prepared in the kitchens directly below the Great Hall; within the kitchen as four long tables directly aligned with the house tables in the great hall above.
At meal times the food is magically transported up, giving the façade of appearing for the students. The majority of the food prepared are traditional British dishes.
However the house elves can accommodate to visitors; during the Triwizard Tournament, foreign dishes such asbouillabaisse and blancmange were served.
The usual beverages include water, milk, tea, coffee, orange juice, and Pumpkin juice. Butterbeer was served during the Yule Ball.