(Reuters) - Brazil's Carnival is a riot of drinking, dancing and partying, symbolized worldwide by the near-naked samba queens who strut their stuff in the parades through Rio de Janeiro's purpose-built Sambadrome.
Carnival in Rio gets going on Friday when the mayor gives the keys to the city to King Momo, the Lord of Misrule. It runs through Ash Wednesday.
* HISTORY: Rooted in ancient festivals, Brazil's modern Carnival dates back to the 18th century and mixes the traditions of Portuguese settlers with the African culture of the slave population. The first parade of samba schools was in 1928. Carnival is supposed to usher in the 40-day partial fasting period of Lent observed by many Christians that leads up to Easter.
* SAMBA SCHOOLS: The top 12 samba organizations, known as schools, parade in Rio's Sambadrome stadium over Sunday and Monday nights to compete for the champion's crown -- a contest that is taken extremely seriously by Brazilians. Rio residents will often support the same samba school fiercely throughout their lives with the same passion they show for soccer.
Each school features up to 6,000 drummers, dancers and other participants as well as spectacularly decorated floats. The schools develop an allegorical theme, or enredo, with a specially written samba song. Salgueiro is the reigning champion.
* QUEENS: Each school has a rainha, or queen, who leads the drum corps. Usually dressed in little more than a huge plumed headdress and high-heeled shoes, they are often famous actresses or models.
* BLOCOS AND BANDAS: Bands and social groups that take part in street parades are an important part of keeping traditional Carnival alive as critics say the Sambadrome parades, where the best seats can cost up to $1,000, have taken it away from the people's reach.
* WHERE THEY ARE: Carnival in Salvador, in northeastern Brazil, now competes with Rio for popularity with much of the action taking place in the streets where "trio eletricos" -- musical combos on the back of trucks -- play to the crowd. The historic town of Olinda, near Recife, also has a noted Carnival.
Similar celebrations also take place in Venice, Italy; the U.S. city of New Orleans, where it is called Mardi Gras and celebrated on Shrove Tuesday; and across Latin America and the Caribbean, with Trinidad's being especially colorful.
Editing by Eric Walsh