The adage "sruti mata laya pita'' refers to sruti as the mother and laya as the father of Carnatic music; they are integral to the music.

There is no absolute rule for selecting the base sruti in a concert. It is selected by the main artiste, and remains constant for the whole duration of the concert. The selection of the base sruti depends on the range of the artiste's voice (in a vocal concert) or on the range of the instrument (in an instrumental concert). The accompanying artistes tune to this base sruti, in order to perform in unisonal harmony. The tampura (or, drone instrument) is also tuned to the base sruti and creates a meditative mood through its resonating and reverberating drone.

The raga is a form of melody and is the central concept in Indian classical music. The notes of a raga are transposed relative to the base sruti that is chosen for the concert. The semantics that describe a raga are highly intricate; even the slightest hint of a wrong note, or even a quarter note, may invoke the theme of a different raga altogether. In the composition "swara raga sudharasa", the composer, Tyagaraja writes, "To discern the homes of the seven notes in the midst of the chaotic uproar is liberation".

Rhythm, or laya, is an important facet of Carnatic music. The generic concept of laya may be expressed in terms of tala (the organization of beats according to predefined rules) and speed. Apart from the raga, the composer of a song also specifies its tala and its speed.

A composition in Carnatic music is a piece of measured music set in a particular raga and tala. Most compositions are generally made up of three distinctly identifiable sections: pallavi, anupallavi and charanam. A section called chittaswaram, which normally follows the anupallavi, can augment certain compositions. The chittaswaram section is a defined organisation of solfa syllables pre-set for a number of tala cycles and may be performed in multiple speeds. Each section of a composition leads the performer into structured sequences of progressively complex melodic and rhythmic variations, while providing ample scope for improvisation. The pallavi is repeated at the end of each of the other sections and is generally ornamented by a completion theme (or teermanam), performed by the percussionist. Each of the sections can begin at any point in the tala cycle (on or off the beat). A section can be sung any number of times with pre-set or sometimes, extempore variations of lines of prose.

Carnatic music is based centrally on a prodigious number of compositions, most of which may be attributed to Tyagaraja, Muthuswamy Dikshitar and Shyama Shastri, three prolific 18th century composers, collectively known as the 'Trinity' of Carnatic music.

In the Vedic period of Indian civilization, music was broadly divided into marga sangeetham (classical music) and desi sangeetham (folk music). It is believed that marga sangeetham was practiced by the deva-s (Gods) and sages (like sage Narada and Thumburu) as music that led one along the path (marga) of mukti (spiritual salvation).

It is no wonder then, that most compositions express intense religious sentiment. The music either evokes spiritualism through the musical content, or directly suggests it through its lyrics.

Compositions

Some of the major types of compositions are: varnam, kriti, keertana, and tillana.
A varnam is a composition that is performed at the commencement of a concert. It is an elaborate melody, replete with emotion. The lyrics of a varnam are comparatively simple and may relate to devotion or to divine love. A varnam could even be in praise of a patron. It requires great skill, technical capacity and creative faculty of a high order to compose varnam-s. Hence, there are very few composers of varnam-s. The constituent anga-s (parts) of a varnam are, in order, pallavi, anupallavi, mukthayiswaram, charanam and charanaswaram.

A composition that relies mainly on its musicality is a kriti and one that relies mainly on its poetic content is a keertana. A keertana is verbose and directly invokes the spiritual emotion using its prose.

A kriti is a highly refined form of composition. The elastic nature of this form, coupled with the fewness of rules, provide extended avenues for the composer's creative genius to be displayed. Kriti-s stand as examples of absolute music. They contain apt themes for developing improvisational routines. A pallavi, anupallavi and charanam are the minimum and essential anga-s of a kriti. A kriti pays a great deal of importance to raga bhava (the emotion evoked by the raga) and the raga lakshana (the characteristic grammar of the raga). It normally consists of very few words. Although the lyrics in a kriti may be free from doxological constructs, many composers shun secular, ethical, social, esoteric or didactic themes and resort to sacred and religious themes. Hence the immortalisation of great composers of the past as Saints. Examples are Saint Thyagaraja and Saint Purandara Dasa.

A tillana is a short and crisp form of music that is rendered at the close of a Carnatic music performance. It is used in dance and incorporates rhythmic syllables directly as text. In most tillana-s, the first two lines of the charanam contain lyrical text.

There are also other forms of compositions, like padam-s and javali-s. These types of compositions often include romantic or Byronic themes.

Other forms of compositions include: bhajan, devaranama, tirupugazh, tevaram, swarajati, viruttam and slokam.