all of these schools are divided in tiers - there is the grupo especial comprising the best 12 schools, and then groups a, b, c, and d, in descending order of size and sophistication, all part of the grupo rio.

what all these schools have in common, is that they all compete against one another to move up in the ranking, aiming at eventually parading in the sambódromo .

many samba schools, especially the ones in the groupo rio, started out as blocos de enredo.