Milonga is a term for a place or an event where tango is danced. People who frequently go to milongas are sometimes called milongueros. The term “milonga” can also refer to a musical genre or a style of dance related to tango.
The music played is mainly tango, vals and milonga (as the musical genre). Most milongas are held on a regular basis (usually weekly), and they often begin with dancing classes and sometimes demonstration dances. Usually, three to five songs of a kind are played in a row (this is called tanda) followed by a short musical break (called cortina) to clear the dancefloor and facilitate partner changes. There are a number of informal rules that dictate how dancers should choose their dancing partners and navigate the floor. – Wikipedia
Códigos (codes) are the dance etiquette that developed over the years in the milongas of Buenos Aires. To people seeing the códigos for the first time, it may seem like a frustrating, long list of rules to be memorized. But those that take to time to review them will find that they are all common sense and will help dancers through unfamiliar situations with ease.
As milongas (tango dance parties) transitioned from live orchestras to music played by a DJ, a tradition evolved of playing music in sets, called tandas, separated by cortinas (literally “curtain,” like the closing of the curtain between acts of a theatrical play). Tandas are sets of 3 or 4 songs played by one orchestra. Tango tandas are usually 4 songs, while Vals and Milonga tandas are 3 songs. Tandas normally consist of music from the same orchestra, in the same era, and the same singer if there is one. This gives the dancers assurance of what music will play throughout the tanda. The cortina between tandas is a short piece of non-tango music. – Siempre Milonguero