Carnival (see other spellings and names) is a festive season that occurs before the Christian season of Lent. The main events typically occur during February or early March. Carnival typically involves a public celebration and/or parade combining some elements of a circus, masks and public street party. People wear masks during many such celebrations, an overturning of life's normal things. The celebrations have long been associated with heavy alcohol consumption. Many synods and councils attempted to set things "right". The statements of Caesarius of Arles (470–542), which protested around 500 CE in his sermons against the Pagan practices, seemed to have formed the building blocks of the Indiculus superstitionum et paganiarum (small index of superstitious and pagan practices), which was drafted by the Synod of Leptines in 742 in which the Spurcalibus en februario was condemned.
Pope Gregory the Great (590–604) decided that fasting would start on Ash Wednesday. The whole Carnaval event was set before the fasting, to set a clear division between the pagan and the Christian custom. It was also the custom during Carnaval that the ruling class would be mocked using masks and disguises. The term Carnival is traditionally used in areas with a large Catholic presence. However, the Philippines, a predominantly Roman Catholic country, does not celebrate Carnival anymore since the dissolution of the Manila Carnival after 1939, the last carnival in the country. In historically Lutheran countries, the celebration is known as Fastelavn, and in areas with a high concentration of Anglicans and Methodists, pre-Lenten celebrations, along with penitential observances, occur on Shrove Tuesday. In Eastern Orthodox nations, Maslenitsa is celebrated during the last week before Great Lent. In German-speaking Europe and the Netherlands, the Carnival season traditionally opens on 11/11 (often at 11:11 a.m.). This dates back to celebrations before the Advent season or with harvest celebrations of St. Martin's Day.
Rio de Janeiro's carnival is considered the world's largest, hosting approximately two million participants per day. In 2004, Rio's carnival attracted a record 400,000 foreign visitors.(Wikipedia)