A samba school (Portuguese: Escola de samba) is a club or dancing school. They practice and often perform in huge square-compounds ("quadras de samba") devoted to practicing and exhibiting samba, an African-Brazilian dance. The schools (which are structured more like a guild than a school in the usual sense) have a strong community basis and are traditionally associated with a particular neighborhood. They are often seen to affirm the cultural validity of the Afro-Brazilian heritage in contrast to the mainstream education system., and have evolved often in contrast to authoritarian development. The phrase "escola de samba" is popularly held to derive from the schoolyard location of the first group's early rehearsals. In Rio de Janeiro especially, they are mostly associated with particular shanty towns ("favela"). Samba and the samba school can be deeply interwoven with the daily lives of the shanty-town dwellers. Throughout the year the samba schools have various happenings and events, most important of which are rehearsals for the main event which is the yearly carnival parade. Each of the main schools spend many months each year designing the theme, holding a competition for their song, building the floats and rehearsing. It is overseen by a "carnavalesco" or carnival director. From 2005, some fourteen of the top samba schools in Rio have used a specially designed warehouse complex, the size of ten football pitches, called Samba City (Cidade do Samba) to build and house the elaborate floats. Each school's parade may consist of about 3,000 performers or more, and the preparations, especially producing the many different costumes, provide work for thousands of the poorest in Brazilian society. The resulting competition is a major economic and media event, with tens of thousands in the live audience and screened live to millions across South America.
The formal parades ("desfiles") during carnival, a uniquely Brazilian phenomenon, are a showcase of each main "escola" enhanced by the participation of celebrities, fans and guests who often pay large sums of money for their elaborate costumes. In Rio de Janeiro and São Paulo, the formal parades are held in specially constructed arenas called Sambadromes (Sambadrome Marquês de Sapucaí in Rio, and the Anhembi Sambadrome in São Paulo) designed by influential architect, Oscar Niemeyer. The Sambadromes are designed to accommodate all social classes, with VIP lounges, tourist sections, and various types of seating right down to cheapest seats for poorest sections of the community. Those who choose to only watch the parade may also be charged for the best seats. Each school displays glamour in colorful costumes and floats with special effects and is organized into different segments or "alas". The "alas" represent different components of the school's theme, or "enredo", as they act out a homage to a myth, historic event or figure, or express their view on a social, environmental or international issue. The "alas" display distinct costumes or "fantasias" and also reflect traditional samba school roles developed years ago. Thus, each samba school parade has the "comissao de frente"; individuals who open the parade by walking in social attires, saluting the crowds; the "ala das Baianas", or the traditional segment of Bahian African-Brazilian ladies with impressive round dresses spinning through the avenue; the "puxadores" (lead singers) singing the "samba-enredo" or theme-song while they play the "cavaquinho" or other string instruments; the "velha guarda", or veterans who made history in the school; the "bateria", or samba band with drums, "cuicas" and other instruments, preceded by the "madrinha da bateria", or band godmother who is often a sexy female celebrity. The "porta-bandeira", or the female flag holder, and the "mestre-sala", or male cortsy, display and salute the school's flag, as they dance and strive to show harmony and samba expertise, as their performance is carefully observed and scored by the judges.