Raaga is an imperative concept in Indian music. It defies precise definition, because its nature can only be grasped in terms of its impact and implications. Though a concept at one level - meaning it has a melodic and technical nucleus - at another it is an abstract and poetic icon, on which the performer or the trained listener contemplates and ponders over. Musicologists inform that in no other system of music does one come across a similar concept or notion. Despite the constant inflow of various kinds of music into the sub-continent over the centuries, the raga concept remained untainted.

Raaga is the oldest and most durable of Indian melodic edifices. The word raaga is derived from the word ranja, which stands for `that which delights or enchants the mind`. Raaga also means a spectrum of colours, a sunburst of emotions and passions, implying thereby the emotional effect created by characteristic melodic movements. Sarangadeva in Sangeet Ratnakara defines a raaga as that which generates pleasure in the listener`s mind through the appropriate use of notes, sound modulations and tonal colours. Matanga in Brihhadeshi characterizes a raaga as `a combination of notes illustrated by melodic movements, which is producing pleasant sensations`.

A number of raagas are derived from folk, tribal or regional tunes and melodies. These tunes and melodies were the first efforts by humans to express their most abstract and concrete feelings and emotions, vocally or instrumentally, using a certain pattern of notes. With the passage of time, these tunes were grammatically tidied, formally stylized and transformed into raagas. This hypothesis is borne out by the fact that several raagas bear the traces of their origin in their names. For instance, Multani, Jaunpuri, Gaud, Sorath, suggest place names; Maand and Pahadi, regions, Ahiri, Gurjari, Asavari imply tribal origins; Zilaf and Shahana indicate Islamic borrowings; Bhairav, Shankara, Kedar, Durga and Saraswati are named after Hindu deities; Mian Malhar, Charju-ki-Malhar and Bilaskhani Todi suggest the names of their creators. Thus the rise of the concept of the raaga owes much to several sources and has also been conditioned by several historical alterations in Indian society. Till about the 15th century, musicological descriptions and representations demonstrate a theoretical basis, entirely different from what one has today. Historical forces and contacts with new cultures and worldviews may have accelerated such alterations.

Raagas, as comprehended today, is a melodic notion or idea using five notes of the octave in a specific order. The combination of notes form a scale conforming to precise rules of ascent (aroha), with determined resting places, distinct phrasal movements all of which go to evoke the raaga`s emotive content. Each raaga obtains its characteristic mood through the dexterous use of specific principal notes. During raaga elaboration and development, stress invariably falls on the vadi swara, because it is that which helps one to recognise the characteristic movement of the raaga. It is the note towards which the performer returns recurrently and makes it as evidently attractive as possible. The samvadi or the consonant is secondary to the vadi, serving to intensify its effect by complementing it. The samvadi is normally positioned in the next tetrachord, generally the 4th or 5th note above the vadi. It sustains the impression created by the vadi in its own tetrachord.

However, it must be borne in mind that a performer treats a raaga as a tonal complex rather than as a grammatical structure, guided by mechanical rules of practice. If a raaga succeeds in evoking a complex of emotions or feelings in the listener`s mind, it is the result of the performer`s skillful and subtle use of certain notes and phrases, which bring forth its emotional content and not his/her mindless recitation of the keynotes.

In Hindustani music it is not uncommon to see more than one raaga having the same set of notes; yet their vadi and samvadi will differ. For instance, Bhoopali, Deshkar and Shuddh Kalyan share the same pentatonic scale Sa Re Ga Pa Dha, but are differentiated on the basis of their differing vadis and samvadis; similarly, with allied raagas like Marwa, Poorya Dhanashri, Poorya and Shree. While elaborating closely related raagas, the performer brings out the differences in mood and impact by emphasizing certain notes and thoroughly avoiding others. The tonal accents too may vary in the case of raagas having the same aroha and avaroha. Many a time, there exists only hairbreadth distinctions between one tonal accent and another, and the risk of `spilling over` into another raaga scale is something skilled performers learn to avoid instinctively. Just as the timbre and tone of voice helps one to differentiate between a request and a command, so the task of a melodic progression, its repeated glidings, waftings towards a tonal centre, would determine its identity.

A singer may choose to bring forth a specific mood or emotion of his choice while rendering a raaga. The debatable point to this very day remains whether a highly skilled performer can, as it were, `infuse` or permeate any mood or feeling of his choice into any raaga; whether raagas are merely grammatical structures, which the performer creatively interprets. Both performers and musicologists believe in the expressive power of swaras. Fro instance, while rendering Bageshri, which is supposed to embody and evoke viraha (pain of separation) and shringar (erotic) rasas, a khayal singer may choose to stress the amorous and romantic moods through distinct melodic movements and evocative song-texts, while an austere dhrupad singer may attempt to depict madhura bhakti (sweet adoration of a deity), resorting to the same technicalities. That said, it is not feasible to make such final statements on aesthetic effect and impact of music, despite designed intentions given that the raaga is a critically organic notion rather than a mechanically attuned series of melodic movements.

Musicians agree that each raaga has a chaal (gait), bearing and personality. Each raaga, they say, has a `face` which it is the performer`s task to `unveil`, show forth evocatively, by repeatedly using its unmistakable melodic phrases. The characteristics phrases, which give the raaga a distinct face, gait and personality, are its pakads or catch phrases, which, along with the grammatical structure lend it a definite identity. While the characteristic movements do call for a certain raaga, they do not de-limit its dynamism in any sense. The personality of a raaga, or the raagabhaava, that shines forth in the art of skilled performers is a fluid and flexible one. Just as no two sculptors can sculpt the same bust alike, so, no two performers can render the same raaga identically.