12 tone music is based off of serialism. Its a theory that says rather than have notes in a key, and as long as you use those notes you are safe, you must put all twelve tones in a particular (serial) order and always sequence your melodies using that order. It doesn't matter what rhthym or timing you use or how the notes flow, but as long as they are flowing in that particular order you are safe. That sense of order is similar to the sense of order you get when using a "key" such as C Major.