Raga a Sanskrit term meaning colour, musical tone. Raga is a harmony of sound and words. Both classical music and classical songs, such as dhrupad, kheyal, tappa, thungri etc are based on ragas. Ragas follow a set pattern of rising and descending notes known as ragalaksan. The singer introduces the raga through a brief alap (prelude). The raga is then elaborated through four stages: sthayi (permanent, the first stage) antara (the second stage), savchari (continuation) and abhoga (return to the first). Nowadays the process has been shortened, with the singer singing only the sthayi and the antara.

There are three divisions of ragas: sampurna, sadav and audav. A raga with all the seven notes in ascent and descent is known as sampurna a raga with six notes in ascent and descent is known as sadav and a raga with five as audav. From these three main divisions there are nine combinations according to the number of ascending and descending notes. These are as follows:

sampurna-sampurna (7 ascending +7 descending)

sampurna-sadav (7 ascending + 6 descending)

sampurna-audav (7 ascending + 5 descending)

sadav-sampurna (6 ascending + 7 descending)

sadav-sadav (6 ascending + 6 descending)

sadav-audav (6 ascending + 5 descending)

audav-sampurna (5 ascending + 7 descending)

audav- sadav (5 ascending + 6 descending)

audav-audav (5 ascending + 5 descending)

A raga possesses the following characteristics: (a) it is created with notes taken from a thata (classification); (b) it has at least five notes with a minimum of two notes from purvabga (the lower half of an octave: notes: sa re ga ma) and uttarabga(the upper half of an octave: pa dha ni sa); (c) its ascending and descending notes follow a set pattern; (d) a raga has vadi, samavadi, anuvadi, vivadi, varjita, jati, pyakada, raga-samay, abga, alap, tal, voltan, vat and sargam; (e) it has the quality to delight listeners; (f) it gives expression to a particular rasa (sentiment); (g) it must use sadaj, the first note of the saptak; (i) no raga can discard both madhyam and pavchamnotes at the same time; (j) no raga should juxtapose shuddha and vikrta forms of notes (however, there may be exceptions).

Ragas can be created in seven ways. The first way has three forms: shuddha, chhayalag (or salabka) and sangkirna. A raga formed with its own elements is called shuddha, for instance bhairav; a raga mixing two ragas is called chhayalag (or salanka), such as shuddha-kalyan and a raga mixing more than two ragas is called sangkirna, such as jaya-jayanti. There are six other ways in which a raga can be created: by altering the mode of a raga (puriya and marva), lending vadi-samavadi to a raga (bhupali and deshkar), altering the komal or kadi notes of a raga (kaphi or puravi), lowering or raising the notes of a raga (shuddhakalyan and bhupali), altering the standing of a raga (darbari kanada and adana), and altering the hour of a raga (suha kanada and nayaki kanada).

Every raga has a propitious time for its rendering. The 24 hours of a day are divided into eight time segments, with different ragas being associated with different periods. The junctures between day and night are known as sandhiprakash time and ragas rendered at these times are known as sandhiprakas ragas. The other ragas are associated with the time of their rendering: morning, midday, evening and night. Thus bhairav (not to be confused with bhairavi) is a morning raga. Each period is dominated by a raga of some particular that. The raga that carries the suggestion of the next that and is rendered while gliding from one that to another is known as paramel-praveshak raga, for example, malgunji, which belongs to the kaphi and khamiaj that. At times several ragas are rendered in a row. This is known as ragamala and it gives the listeners a special delight. Ragas are also associated with different seasons. Basanta for example is associated with spring; malhar is associated with rains, as are its variations such as miaki- malhar and megh-malhar.

The use of ragas in Bangla songs dates as far back as the charyapada, the songs of which were composed to be sung in vishuddha ragas. A fuller use of ragas is found in the later gitagovindam and srikrishnakirtan. The ragas of the Charyapada are patmavjari, bhairav, aru, varadi, gavda, shavari, gurjari, mallari, devakri, gauda, deshakh, gavuda, malsi-gavuda, kamod, kanhu-gunjari, dhanasi, vabgal and ramkri. It is probable that gauda and gavuda are the modern gauda raga and that gauda is the modern gara.

The ragas of the Gitgovindam are gurjari, malavgauda, karnat, deshakh, deshvaradi, gondakiri, malava, vasanta, bhairavi, ramkiri, varadi and vibhas. The songs of the Gitgovindam were composed in these ragas and it was clearly indicated which song was to be sung in which raga and tal. The ragas of Shrikrsvakirtan are aher, vibhas, kaku, vibhas kahu, kahu, velavali, gajjari, bhatiyali, kedar, bhairavi, koda, mallar, koda deshag, malava, deshvaradi, malavashri, deshag, maharatha, dhanusi, ramgiri, patamanjari, lalita, pahadia, shauri, vabgal, shri, vangal varadi, shriramgiri, varadi, sindhoda, vasanta and kahu-gurjari. Even today these ragas are in use and are quite popular, though many have undergone some change of nomenclature. For instance, koda is now familiar as kaunsikanada.

Indian music is divided into North Indian (Hindustani) and South Indian (Daksini) music, with Bengali music generally following the North Indian style. However, many Bengali composers, including rabindranath tagore and kazi nazrul islam, have introduced south Indian ragas into Bangla songs and have experimented with different ragas. Nazrul Islam not only popularized raga-based Bangla songs, he also created some new ragas and composed songs in them. Among the ragas he created are venuka, dolanchanpa, devayani, sandhyamalati, vanakuntala, minaksi, yogini and nirjharini. [Mobarak Hossain Khan and Krishnapada Mandal]