The Carnival of Venice, or Carnevale di Venezia in Italian, is an annual festival that starts two weeks before Ash Wednesday and ends on Shrove Tuesday. This year, Carnevale took place February 6 - 16. The history of the Venice Carnival tradition began after 1162. The Republic defeated Ulrico, Patriarch of Aquileia in that year, and began a tradition of slaughtering a bull and twelve pigs in the Piazza San Marco around Shrove Tuesday to commemorate the victory. This celebration gradually grew and 1268 dates the first document mentioning the use of masks.
Masks made the Venetian Carnival unique. If you cannot identify the wearer of the mask, you do not know his social status. In this way, Venice temporarily overturned her social order. Some of the masks depicted Commedia dell'Arte characters. Others were more sinister. The white-beaked mask so famous from photographs is that of the plague-doctor; the beak echoes a doctor's long breathing apparatus that held a sponge doused in vinegar, thought to hold the plague at bay. The Doges were frequently exercised by the dangers masks allowed, and passed laws limiting their use to within the carnival period; if you wore a mask at any other time of year, penalties were severe.
People in elaborate costumes and Venetian masks fill the streets in one big party that fills every crevice of the island and is like a mixture of Mardi Gras and Halloween! Those with the most elaborate costumes are invited into the costume parade in Piazza San Marco.