The lifeblood of all Indian classical music, whether Hindustani (North Indian) or Carnatic (South Indian), is the concept of raag (in English, spelt and pronounced ‘raga’ after its Sanskrit form - although in modern North Indian languages the 'a' at the end is quite redundant).

The word raag is derived from the Sanskrit word rang which means ‘colour’ in many Indian languages. So we can say a raag is that which 'colours the mind' with a particular emotion. There is no single English word that can accurately translate the full meaning of raag. It is not a musical scale, a mode or even a tune, but it definitely encompasses all those three elements. So, rather than attempt to describe the concept of raag in its totality, it is easier to look at it from the perspective of what it must contain to qualify as a raag. A raag must have notes – musical notes known as swara or simply sur in modern Hindi or Urdu. As in Western music, there are seven main notes, drawn from a similar basic set of twelve tones to the Western piano. A raag can contain some or all seven notes, and can have different numbers of notes in its ascending and descending scales. The rules governing which notes may, or may not be used in ascent (aroha) or descent (avroh) form a large part of the grammatical rules for how to correctly execute a performance of the raag. In addition, the rules are further clarified in that individual musical notes contained within a raag are not all given equal significance. Some are more important (or dominant) than others - the most important is called vadi (king note) and the second most important one is samvadi (queen note), and numerous complex rules dictate how these notes may be driven - such as chalan, which means ‘walk’ or ‘arrived at’ within the melody. Raags are sometimes also defined or categorised in terms of particular characteristic movements of notes, resulting in distinguishing phrases that make a particular raag stand out from another one with similar note combinations. There are over 500 known raags but we usually only hear the same favourite few dozen or so.

Raags are also ascribed to a particular time of day or night (known as prahar), but with concerts mostly taking place in the evenings, it is becoming rarer to hear live recitals of early morning or afternoon raags. Novices will at first find it difficult to identify individual raags, but those who listen to Indian music regularly and with systematic concentration soon learn to recognise their favourites. A detailed musical or technical knowledge, however, is not necessary for the enjoyment of Indian classical music as it is primarily aimed at the heart rather than the brain. Many raags are designed to work like a prescription, enhancing a particular mood, time of day, season, emotion or ambience.

Listen to the music | Young sitar virtuoso Niladri Kumar explains the concept of raag, demonstrating the ideas on his sitar as he goes.

Jameela Siddiqi is an author, linguist, and BBC cultural commentator, specialising in postcolonial fiction and the devotional music of South Asia.

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