What is the basis for writing music in the twelve-tone system?

Answer 1

Twelve-tone music uses a "row" as opposed to a "scale" or "mode" for its melodies and harmonies. The composer constructs a row by putting the twelve semi-tones of the octave in aparticular order - and depending on what order it will (to an extent) govern the overall feel of the piece. The notes of the row are then used to compose the piece; each note appearing in order throughout it. The composer can manipulate the row by using compositional techniques like inversion and retrograde, among others. Plus, there are a number of rules that allow for certain exceptions and repeated notes.

The whole idea behind 12 tone music is to have all twelve notes constantly circling so that no one note takes precedence over the others like the tonic does in tonal music. This creates an ambiguous tonality and the composer can concentrate on motifs and textures without worrying about which note is supposed to comes next (however, in practice, I have found that composers probably spend even more time thinking about note choice using 12 tone than they do writing tonal music).