Indian classical music is categorized under two genres. These are Hindustani and Carnatic. Broadly speaking, Hindustani developed in the northern regions of the country, while Carnatic music is indigenous to the south.
There are three main components to the classical music of india - drone, raga, and tala.
Unlike western musics, indian music is not based on harmony. The harmonic princple of contrast between simultaneous sounds is foreign to the indian conception of music. The concept of modulating (or changing) keys is also absent. Instead, the music is based on a drone, a continual pitch that sounds throughout the concert. This acts as a point of reference for everything that follows, a home base that the musician returns to after a flight of improvisation.
Raga - organization of Melody
"Raga" is one of those annoying words which has no equivalent in english, and is thus also frustratingly difficult to define. Terms like "generalized melody" or "melodic framework" are perhaps the best english descriptions, although they are only somewhat helpful. I like to describe a raga as being about halfway between a scale and a tune. A scale is just a set of notes, which can be used in any way you want. A tune leaves no room for spontaneous creation of melody. A raga lacks the total freedom of a scale, but has much more freedom than a tune.
A raga may be characterized in a number of ways. It is built out of a specific selection of tones from the octave (at least five), like a scale. But in a scale all notes are equal. Ragas have more and less important notes. There may be characteristic phrases that are used in the performance of the raga, or specific ways in which the notes cannot be used. Each raga is also associated to a particular mood, and to a particular time of day or season of the year.
The result is a melodic structure that is easily recognizable, yet infinitely variable. No two performances of the same raga, even two performances by the same musician, will be identical. Indeed the same raga may be played by the same musician one night for half an hour, the next night for an hour and a half. Yet the character of the raga, the mood it creates, will still be the same.
Tala - organization of Rhythm
In the same way that ragas are melodic structures, talas are rhythmic structures. The tala can be thought of a cycle, divided into equal beats which are collected into subgroups. So, for example, Rupak tala consists of seven beats, a group of three beats followed by two groups of two beats (sometimes represented 3+2+2). The tala is usually represented by a series of strokes (called "bols") on the Tabla, reflecting the subgroupings within the tala. The tabla player will vary the strokes that he plays, but will do so in a manner consistent with the basic rhythm of the tala. In particular, he will be careful to differentiate between the khali (off-beats) and tali (on-beats), which are defined for each tala.
The most important beat of the tala is the first one, called "sam". In performance, the soloist may go off on a long improvised phrase that may last for many cycles of the tala, but will always return to the composition on the sam. (From Mr Andrew Buhr's A Beginner's Guide to North Indian Classical Music)
Carnatic music is the music of South India, different in many of its terms and formal demands, although similar in overall outline. The two share some common origins, but the details of these relationships can be contentious.
Carnatic music is the classical music of Southern India. The basic form is a monophonic song with improvised variations. There are 72 basic scales on the octave, and a rich variety of melodic motion. Both melodic and rhythmic structures are varied and compelling.
Carnatic music is considered one of the oldest systems of music in the world. Imbued with emotion and the spirit of improvisation, it also contains a scientific approach. This is mainly due to the contributions of such inspired artists as Purandara Dasa, known as the Father of Carnatic Music, and other scholars who codified the system and gave it a clear format as a medium of teaching, performing, prayer and therapy.
Like Hundustani music,the basis of Carnatic music is the system of ragas (melodic scales) and talas (rhythmic cycles). There are seven rhythmic cycles and 72 fundamental ragas. All other ragas are considered to have stemmed from these. An elaborate scheme exists for identifying these scales, known as the 72 Melakarta Ragas.
Carnatic music abounds in structured compositions in the different ragas. These are songs composed by great artists and handed down through generations of disciples. While the improvised elaboration of a raga varies from musician to musician, the structured portion is set. These compositions are extremely popular, with a strong accent on rhythm and lively melodic patterns. Three saint composers of the nineteenth century, Tyagaraja, Muthuswami Dikshitar and Shyama Shastri, have composed thousands of songs that remain favourites among musicians and audiences.
An important element of Carnatic music is its devotional content. The lyrics of the traditional compositions, whether mythological or social in nature, are set entirely against a devotional or philosophical background.