convey are more important in defining a raga than the notes themselves. In the Indian musical tradition, rāgas are associated with different times of the day, or with seasons. Indian classical music is always set in a rāga. Non-classical music such as popular Indian film songs and ghazals sometimes use rāgas in their compositions. According to Encyclopædia Britannica, a raga, also spelled rag (in northern India) or ragam (in southern India), (from Sanskrit, meaning "colour" or "passion"), in the classical music of India, Bangladesh, and Pakistan, is "a melodic framework for improvisation and composition. A raga is based on a scale with a given set of notes, a typical order in which they appear in melodies, and characteristic musical motifs. The basic components of a raga can be written down in the form of a scale (in some cases differing in ascent and descent). By using only these notes, by emphasizing certain degrees of the scale, and by going from note to note in ways characteristic to the raga, the performer sets out to create a mood or atmosphere (rasa) that is unique to the raga in question. There are several hundred ragas in present use, and thousands are possible in theory." Alapa (Sanskrit: "conversation") are "improvised melody structures that reveal the musical characteristics of a raga". "Alapa ordinarily constitutes the first section of the performance of a raga. Vocal or instrumental, it is accompanied by a drone (sustained-tone) instrument and often also by a melodic instrument that repeats the soloist's phrases after a lag of a few seconds. The principal portion of alapa is not metric but rhythmically free; in Hindustani music it moves gradually to a section known as jor, which uses a rhythmic pulse though no tala (metric cycle). The performer of the alapa gradually introduces the essential notes and melodic turns of the raga to be performed. Only when the soloist is satisfied that he has set forth the full range of melodic possibilities of the raga and has established its unique mood and personality will he proceed, without interruption, to the metrically organized section of the piece. If a drummer is present, as is usual in formal concert, his first beats serve as a signal to the listener that the alapa is concluded." Artificial intelligence Machine improvisation uses computer algorithms to create improvisation on existing music materials. This is usually done by sophisticated recombination of