Rio de Janeiro is a major city in southeastern Brazil and the capital of the state of Rio de Janeiro. The city was once the capital of Brazil (1763–1960) and of the Portuguese Empire (1808–1821). Commonly known as just Rio, the city is also nicknamed A Cidade Maravilhosa - "The Marvelous City". The population of the City of Rio de Janeiro is about 6,094,183. . It is Brazil's second-largest city after São Paulo and was the country's capital until 1960, when Brasília took its place. Residents of the city are known as Cariocas.

Rio de Janeiro is among the biggest cities in South America, but the city is more widely renowned for the various cultural celebrations that are held there every year. The most popular of these is the Carnaval, held two weeks before the traditional Christian fasting of Lent. Rio de Janeiro has many Carnaval choices, including the famous Escolas de Samba(Samba schools) parades in the sambódromo exhibition centre and the popular 'blocos de carnaval', which parade in almost every corner of the city. The celebration of Carnival ends on "Mardi Gras" Tuesday. Rio also has one of the world's most talked-about nightlife. Rio has a lot of nightclubs where the rich enjoy themselves and party the night away.

Guanabara Bay natural beauty, combined with the fame of the Copacabana Palace Hotel, the luxury hotel of the Americas in the 1930s, helped Rio to gain the reputation it still holds today as a beachy party town. The city is commonly divided into the historic downtown (Centro); the tourist-friendly South Zone, with world-famous beaches; the industrial North Zone; and the West Zone, with the newer Barra da Tijuca district.

More notable sports events in Rio include the MotoGP Brazilian Grand Prix and the World Beach volleyball finals. Sports are a very popular pastime in Rio de Janeiro. The most popular is futebol (football/soccer). Rio de Janeiro is home to four traditional Brazilian football clubs: Botafogo, Flamengo, Fluminense and Vasco. Other popular sports are beach football, beach volleyball, surfing, kitesurfing, hang gliding, motor racing, jiu-jitsu, recreational sailing, and competitive rowing. The peculiarly Brazilian dance/sport/martial art Capoeira is also popular. Another sport that is highly popular on the beaches of Rio is called "Fresco Ball" (or Matkot), a type of beach tennis. Rio de Janeiro is also a paradise for rock climbers, with hundreds of routes all over the town, ranging from easy boulders to highly technical big wall climbs, all inside the city.