Iranian/Persian traditional music (also known as "mūsīqī-e sonnatī-e īrānī" or "mūsīqī-e aṣīl-e īrānī") is now modernly classified into the Dastgāh system. This system is a modal system, in the fact that it utilizes distinct modes of music, in this case seven. Each of these seven modes, referred to as "Dastgāh", are then classified into smaller units (usually only one), each called an "āvāz". Every "āvāz" consists of short pieces and melodies of music called the "gousheh" that, although each has its own characteristics, share one central characteristic in the "āvāz".
The seven main "Dastgāh" of Iranian music are modernly known as "Shour", "Māhour", "Homāyoun", "Segāh", "Chāhārgāh", "Rāstpanjgāh", and "Navā". Each of these seven is considered to be its own "āvāz". Yet, "Dastgāh-e Shour" also contains the four "āvāz-e Abou'atā", "āvāz-e Bayāt-e-Tork", "āvāz-e Afshāri", and "āvāz-e Dashti" along with its own "āvāz-e Shour". Similarly, "Dastgāh-e Homāyoun" contains both "āvāz-e Homāyoun" and "āvāz-e Esfahān". "Shour" is mainly considered the mother of all "Dastgāh". 
The classification is as below:
A complete book in Iranian traditional music is called the "radif", which consists of all seven "Dastgāh". Such a "radif" would traditionally be written by the master, the "ostād", and then played, learned, and thoroughly memorized by the apprentice before he could become a master. Each "radif" consists of approximately 200–400 "gousheh".