A Samba School in the Brazilian tradition is a community group focussed on samba culture - dance, percussion, music - and embodied in an annual Carnival. The Samba School is a family which hands this samba culture down through the generations - hence the essential groups of Mirim (children) and Baianas (ladies), and the Velha Guarda (veterans).
In Brazil, Samba Schools exist only in Rio de Janeiro and Sao Paulo and have well defined structure and traditions. Whilst samba is simply not well known enough outside Brazil for organisations to be as large, these are the characteristics which would make an organisation recognisable as a Samba School to a Brazilian:
The School must take part in a carnival once a year which includes:
An Ala Baiana;
A Samba Enredo (samba theme song) which is specially composed each year for the carnival;
An Ala Mirim;
Each samba school adopts two or three primary colours that are reflected in their carnival designs. In addition to these, each samba school is permitted to use gold, silver, black and white. In practice, however, they also use secondary colours when developing their theme. The chosen primary colours are related to the Orixas (Afro-Brazilian deities, from Candomblé - a mixture of Christianity and African religions).
In Rio Carnival, there is a defined structure for the different elements of the parade which has evolved over several decades, and which is adhered to by all groups competing. Each samba school has a history of its own but also fits into the history of carnival. There are traditional procedures although only the glorious spectacle should be evident to the spectators.
Every year, each samba school chooses a theme. This often reflects the everyday concerns of ordinary people, be these political, joyous, critical of the society in which we find ourselves etc, and are frequently irreverent, but always, always luxurious. Depending upon the theme, the parade may include elements of many other performing arts, from ballet to circus, etc. The different influences which are recognisable in the carnival samba of today, are African, European and from the native peoples of Brazil.
The general form of the Bateria always conforms to certain traditions but within these, each Samba School has its own musical tradition and recognisable style.