The Structure of a Milonga
Music at a Milonga (tango dance) is arranged into “tandas” and “cortinas”.
Tandas are sets of 3 or 4 songs played by one orchestra or songs that are similar in nature. It is polite to dance the full tanda with the same person. However, if you begin dancing part way through a tanda you still end at the cortina.
Cortinas are short bits of music that indicate it’s time for a break. The cortina signals the end of the tanda. This is where the leader would most likely escort the follower back to her seat. A Cortina should sound very different than music during a Tanda.
During a milonga, there will be tandas of Tangos, Milongas and Valses. Typically, the more lively music is played earlier and, as the night progresses, more dramatic music is played. However, this is not a hard and fast rule as a DJ might want to add a lively Tanda to liven up the crowd.