How the music is organized, structured; the number of s and the way they are constructed, the number of s and s in each, and the order they are performed. Unique sections are labeled , “A”, “B”, “C”. Sometimes there is an Introduction, , or – an ending bit.
Composers/arrangers make a very conscious decision regarding form. The order sections are heard greatly effects our sensations and responses as listeners and dancers.
The way s order the sections in performance is quite varied. Often some sections are played more than once. So, although there may be only two distinct sections, say A and B, the orquesta may play A-B-A-B-A. Or if there are three sections, maybe A-B-A-C-A, etc. The combinations are numerous. Usually the second, or third, playing of a section will be different than the first; there may be different instrumentation or accompaniment, or the melodic line may be highly elaborated by the bandoneons (called a variación), which frequently happens during the last time through section A.
When there is a singer it is usual for one or all the sections – A,B, maybe C – to be instrumental; no voice. At some point the singer sings the lyrics for one or two sections. Section A or another one is usually played instrumentally at the end.
Sections are the top level element of music's form. They are the the large building blocks of tango music, typically lasting around thirty seconds or so. Each section is a unique segment of music, having a distinct musical character.
Tango music has two, occasionally three, primary sections, which we may label “A”, “B”, “C”. Sometimes there is an "Introduction", "Bridge", a short section between two larger ones, or "Coda", a short concluding section.
Usually each section will be played consecutively in order (A then B then C), followed by various other orderings. Typically in tango songs each section is played instrumentally then each is sung, then section A is played instrumentally: A-B-A (vocal)-B (vocal)-A. But there are many exceptions and other possibilities.
Phrases exist within a section.
A bar or measure is a small segment of music containing all the number of beats as specified by the time signature.
A short section of music with a clear start and end quality, with a consistent or complementary musical character. Generally, the character is different from what comes after or precedes it, anywhere from subtly to very obvious. more...
In terms of form, a bridge is a short section used to connect two other larger sections. Usually the musical character is different but complementary and may contain elements from the preceding section and/or the next one. It is literally a "bridge" between them.
In terms of form, a coda (Italian for "tail") is a short section used to end a piece of music.
An orquesta típica is an ensemble of musicians who play tango music. Typically, there is a string section, a bandoeon section, a piano, and sometimes a singer or two. There is no specific rhythm section – no drums or other percussion instruments. An orquesta típica is an expanded version of a sexteto tipico, which includes 2 bandoneons, 2 violins, double bass, and piano.
I call any band that plays tango, no matter what the instrumentation, an orquesta. Not entirely accurate but it simplifies things.