Indian classical music divides the octave into 12 semitones. In ascending tonal order, the seven basic notes are: Sa, Re, Ga, Ma, Pa, Dha, Ni and Sa. However, Indian Classical Music uses intonation tuning, and is monophonic in nature which is played over a fixed drone. Typically a performance is based on a particular Raga and Tal. The different Ragas are supposed to be sung or played at a particular time of the day or season. It is said that the Raga is the most effective when sung or performed in such a manner.