Unlike most Western classical music, most Indian classical music is improvisational. The musician chooses a raga and a tala. These provide a basis for the musician to improvise a solo. This is a little similar to the way the chord progression and the background provided by the the rhythm section of a jazz band give the jazz soloist the basis to improvise a solo. Of course, both the basis and the rules for improvising are different from jazz, so the results also sound very different.

The melodies and harmonies in Western music are based on major and minor scales. Major-key melodies and harmonies are different from minor-key melodies and harmonies, but the same melody and chord progression can be easily transposed from one major key to a different major key, or from one minor key to a different minor key. Of course, some Western music is modal, and some uses pentatonic, blues, twelve-tone, or other scales, but the vast majority of familiar pieces can be classified as major or minor.

The melodies of Indian music are based on ragas (in southern India, ragam). Like a scale, the raga is a list of the notes that are used in a particular piece of music. But there are many more ragas than there are scales - hundreds - and the various ragas are much more different from each other than the various scales are. The number of notes used, the intervals between the notes, and even the tuning, can be different from one raga to the next. Because of these differences, the rules for constructing melodies are also different in different ragas, and so the melodies found in various ragas will not be the same. A melody cannot be transposed from one raga to another; they are simply too different.

You may have noticed that major-key music tends to have different moods than minor-key music. (See Major Keys and Scales for more about this.) Ragas are also associated with particular moods. The idea that different modes produce different moods is one that was also common in ancient and medieval Europe. Many ragas are also associated with a specific season and/or time of day. These associations often began with traditions of playing certain ragas for particular festivals or religious rites, but the associations with moods are also tied into the associations with particular times. (Think of the difference between your typical mood on a summer evening as opposed to an autumn morning.) It is often considered inappropriate to play a raga at the wrong time (similar to a Westerner's reaction at hearing Christmas music in July, lullabies at breakfast, or sad songs at a wedding), and creating the raga's proper mood is one of the Indian musician's most important tasks.

If you don't mind getting a little technical, there is more information on raga at Indian Classical Music: Tuning and Ragas.

Much of the interest in Western music lies in its complex, ever-changing harmony. Indian music takes a different approach. Melodic scales and rhythms are much, much more various and complex than they are in Western music. Harmony, on the other hand, is usually kept simple, in the form of an unchanging drone of a pure perfect fifth or perfect fourth. (See below for more about the drone instrument.)

In order to fit better with the pure interval of the drone, the tuning system used is not equal temperament; instead a just intonation system, based on the pure fifth, is used. The tuning of the other notes (the ones not played by the drone) can vary to suit the particular raga. For more technical information on tuning, please see Tuning Systems and Indian Classical Music: Tuning and Ragas.

Western music tends to use only a few popular meters for almost all of its music, and these meters are usually felt as repetitions of two, three, or four beats. The rhythms of Indian music, rather than being organized into short measures, are organized in long rhythmic cycles called talas (in southern Indian thaalam). There are more than 100 different talas. These rhythmic cycles are quite long and complex; the Carnatic tradition in particular includes some of the most complex and sophisticated rhythmic structures of any music tradition.

In fact, it is common for some sections of a performance (see below) to be in free rhythm, with the tala not even introduced until the middle of the piece. These free-rhythm performances, which altogether lack a beat-like pulse, are central to a true appreciation of Indian music. Gosvami suggests (1961, p. 162) that "the best way to approach the Indian rhythm is to pay attention to the phrasing and ignore the pulsation", claiming that Indian rhythm is "derived from song", while Western rhythms are derived from "the dance or the march" (p. 169).

Indian music is indeed, in many ways, based on the song. While Western audiences are more likely to hear famous Indian instrumentalists, vocal music is actually at the center of the Indian tradition, and vocal techniques are understood to be the basis for good instrumental technique.

The texture of Indian music is typically a single melody voice or instrument, supported by drones and rhythm percussion. As mentioned above, this texture is not common in Western music, and there are several elements of the timbre (color) of the music that also make it sound unfamiliar. One is, of course, the use of Non-western instruments, as described below. But even the tone quality of the voice is different from the typical Western vocalist, who usually strongly relies on vibrato to produce an acceptable tone quality. The Indian vocalist, on the other hand, tends to use a timbre lacking in vibrato. To Western listeners, this tone quality may at first sound flat, nasal, or lifeless. However, to the Indian listener it is a clean, clear sound that does not mask the subtleties of the ragas tuning, or overpower or interfere with the production of the intricate ornaments that are also an integral part of each raga.

Because instrumental techniques also rely on these subtle tunings and ornaments, Indian instruments also tend to play with little or no vibrato.

The harmony is usually provided by a drone instrument called the tanpura. (There are many alternative English spellings for the name of this instrument, including taanpura and tambura.) This instrument has four very long strings. The strings are plucked one after the other, continuously throughout the music. It takes about 5 seconds for one four-string cycle to be plucked, and although the drone itself is constant, the complex interactions between the harmonics of the strings vary during the cycle, creating a shimmering, buzzing effect unlike that of any Western instrument.

In India, vocal soloists are very popular, but Westerners tend to hear instrumental soloists. The melody instrument is often also a stringed instrument: the most well-known is probably the sitar, a plucked-lute-family chordophone that has moveable frets to accomodate changes in tuning from one raga to the next. Other popular solo strings include the surbahar, which is basically a bass sitar, the sarod, a fretless plucked-lute-family instrument, and the vina, a zither-family chordophone with gourd resonators. On many of these instruments, only some of the strings are for playing the melody. Other strings are drone/rhythm strings and/or strings that are not plucked but only vibrate sympathetically with the other strings. Again, this can produce a buzzing timbre that Westerners find exotic.

There are other, less common solo string instruments. Bamboo flutes (bansuri or venu) are also popular solo instruments, and some Western instruments, particularly violin, are also fairly popular.

The rhythmic accompaniment is usually provided by the tabla, a set of two small drums that are played with the hand. The tabla is tuned to the raga by tapping wedges on the side of the instrument. Because the tabla is played with the hand rather than a stick or beater, the rhythms of the accomplished player are subtle and expressive as well as complex. In fact, even on this percussion instrument, an accomplished Indian musician can put the listener in mind of vocal phrasing.

There are many forms in Indian classical music, including shorter composed songs and hymns. But the form of the fully-explored raga has three main sections.

The opening section, the alap, is a long, slow, free-rhythm improvisation. In it, the performer reveals the raga gradually, note-by-note. Although this section may be hardest to appreciate for listeners accustomed to the relentless rhythms of Western rock and pop, to those who understand Indian music, it is the section in which the musicianship of the great performer is most obvious.

The jor-alap section introduces a rhythmic pulse, and the music becomes more animated.

The percussionist joins in on the jhala section, as the music becomes faster, more rhythmically complex, and more exciting as it drives to its climax. All of these sections are typically improvised, with close communication, cooperation, and interaction between the soloist and percussionist on the improvisation of the final section.