This carnival is an annual festival held forty-six days before Easter. On certain days of Lent, Roman Catholics and some other Christians traditionally abstained from the consumption of meat and poultry, hence the term “carnival,” from carnelevare, “to remove (literally, “raise”) meat.
Rhythm, participation, and costumes vary from one region of Brazil to another. In the southeastern cities of Rio de Janeiro and São Paulo, huge organized parades are led by samba schools. Those official parades are meant to be watched by the public, while minor parades (“blocos”) allowing public participation can be found in other cities.
Look here for pictures from carnival held in 2011. –> Rio de Janeiro carnival 2011