Alapana is a form of melodic improvisation that introduces and develops a raga (musical scale) in Indian classical music. As a term that is Sanskrit in language, alapana means "to speak, address, discourse, communicate". The flavor of the raga is outlined in the alapana by rendering the raga's permitted notes in structures and phrases unique to the raga (known as "raga lakshanam"). Alapana typically precedes a song that is going to be sung in the same raga.
Alapana is rendered in different speeds, with a gradual increase in tempo. Likewise, the complexity of the patterns increases steadily as the alapana progresses.
Alapana is divided into three parts:
In Carnatic music
In Carnatic music, alapana, sometimes also called ragam, is the exposition of a raga or tone - a slow improvisation with no rhythm, where the raga acts as the basis of embellishment. In performing alapana, performers consider each raga as an object that has beginnings and endings and consists somehow of sequences of thought.
In a Carnatic music concert, the alapana introducing a major composition may last 45 minutes or more, while those preceding other compositions are proportionatey shorter. Some ragas like Yadukulakambhodhi revolve around key phrases. Performers and instrumental accompanists often render the alapana together and individually (for example, vocalist's phrases are shadowed by that of a violinist, and later the violinist may perform solo).
In Hindustani music
Hindustani music features percussion accompaniment to raga alapanas once the phrasing has picked up sufficient complexity and tempo. In a concert, alapana typically takes center stage. Entire concerts may be devoted to the exposition of just one or two ragas, with each alapana segment followed by a few lines of a song also improvised within the constraints of the raga's scale and characteristic phrases.