Brazil, officially the Federative Republic of Brazil, is the largest country in South America and a founding member of BRICS. It is also the world's fifth-largest country by area and the seventh-largest by population, with over 213 million people. The country is a federation composed of 26 states and a Federal District, which hosts the capital, Brasília. Its most populous city is São Paulo, followed by Rio de Janeiro. Brazil has the most Portuguese speakers in the world and is the only country in the Americas where Portuguese is an official language.

Bounded by the Atlantic Ocean on the east, Brazil has a coastline of 7,491 kilometers (4,655 mi). Covering roughly half of South America's land area, it borders all other countries and territories on the continent except Ecuador and Chile. Brazil encompasses a wide range of tropical and subtropical landscapes, as well as wetlands, savannas, plateaus, and low mountains. It contains most of the Amazon basin, including the world's largest river system and most extensive virgin tropical forest. Brazil has diverse wildlife, a variety of ecological systems, and extensive natural resources spanning numerous protected habitats. The country ranks first among 17 megadiverse countries, with its natural heritage being the subject of significant global interest, as environmental degradation (through processes such as deforestation) directly affect global issues such as climate change and biodiversity loss.

Brazil was inhabited by various indigenous peoples prior to the landing of Portuguese explorer Pedro Álvares Cabral in 1500. It was claimed and settled by Portugal, which imported enslaved Africans to work on plantations. Brazil remained a colony until 1815, when it was elevated to the rank of a united kingdom with Portugal after the transfer of the Portuguese court to Rio de Janeiro. Prince Pedro of Braganza declared the country's independence in 1822 and, after waging a war against Portugal, established the Empire of Brazil. Brazil's first constitution in 1824 established a bicameral legislature, now called the National Congress, and enshrined principles such as freedom of religion and the press, but retained slavery, which was gradually abolished throughout the 19th century until its final abolition in 1888. Brazil became a presidential republic following a military coup d'état in 1889. An armed revolution in 1930 put an end to the First Republic and brought Getúlio Vargas to power. While initially committing to democratic governance, Vargas assumed dictatorial powers following a self-coup in 1937, marking the beginning of the Estado Novo, in which he oversaw Brazil's involvement in World War II. Democracy was restored after Vargas' ousting in 1945. An authoritarian military dictatorship emerged in 1964 with support from the United States and ruled until 1985, after which civilian governance resumed. Brazil's current constitution, enacted in 1988, defines it as a democratic federal republic.

Brazil is a regional and middle power and rising global power. It is an emerging, upper-middle income economy and newly industrialized country, with one of the 10 largest economies in the world in both nominal and PPP terms, the largest economy in Latin America and the Southern Hemisphere, and the largest share of wealth in South America. With a complex and highly diversified economy, Brazil is one of the world's major or primary exporters of various agricultural goods, mineral resources, and manufactured products. The country ranks thirteenth in the world by number of UNESCO World Heritage Sites. Brazil is a founding member of the United Nations, the G20, BRICS, G4, Mercosur, Organization of American States, Organization of Ibero-American States, and the Community of Portuguese Language Countries; it is also an observer state of the Arab League and a major non-NATO ally of the United States.

The word Brazil probably comes from the Portuguese word for brazilwood, a tree that once grew plentifully along the Brazilian coast. In Portuguese, brazilwood is called pau-brasil, with the word brasil commonly given the etymology 'red like an ember', formed from brasa ('ember') and the suffix -il (from -iculum or -ilium). It has alternatively been suggested that this is a folk etymology for a word for the plant related to an Arabic or Asian word for a red plant. As brazilwood produces a deep red dye, it was highly valued by the European textile industry and was the earliest commercially exploited product from Brazil. Throughout the 16th century, massive amounts of brazilwood were harvested by indigenous peoples (mostly Tupi) along the Brazilian coast, who sold the timber to European traders in return for assorted European consumer goods.

The official Portuguese name of the land, in original Portuguese records, was the 'Land of the Holy Cross' (Terra da Santa Cruz), but European sailors and merchants commonly called it the 'Land of Brazil' (Terra do Brasil) because of the brazilwood trade. Popular usage eclipsed and eventually supplanted the official Portuguese name. Some early sailors called it the 'Land of Parrots'. In the Guarani language, Brazil is called Pindorama, meaning 'land of the palm trees'.

Some of the earliest human remains found in the Americas, Luzia Woman, were found in the area of Pedro Leopoldo, Minas Gerais, and provide evidence of human habitation going back at least 11,000 years. The earliest pottery ever found in the Western Hemisphere was excavated in the Amazon basin of Brazil and radiocarbon dated to over 8,000 years ago (6000 BC). The pottery was found near Santarém and provides evidence that the region supported a complex prehistoric culture. The Marajoara culture flourished on Marajó in the Amazon delta from AD 400 to 1400, developing sophisticated pottery, social stratification, large populations, mound building, and complex social formations such as chiefdoms.

Around the time of the Portuguese arrival, the territory of present day Brazil had an estimated indigenous population of 7 million people, mostly semi-nomadic, who subsisted on hunting, fishing, gathering, and migrant agriculture. The population comprised several large indigenous ethnic groups (e.g., the Tupis, Guaranis, Gês, and Arawaks). The Tupi people were subdivided into the Tupiniquins and Tupinambás.