In Carnatic music, Neraval also known as Niraval or Sahitya Vinyasa is the elaboration and improvisation of melody for a particular line.
Usually, just one or two lines of text from the song (from the anupallavi or charanam part of the kriti) are sung repeatedly, but with improvised elaborations.
[1] The part of lyrics is chosen which is self-contained in terms of its meaning and context and has an elegant structure amenable for repetition with variations.
In general, such elaboration follow the rhythmic patterns in the original lyrics (talam),[2] and each word in the lines of text stay set within their original place (idam) in the tala cycle, [3] though minor variations that remain faithful to the syllabic patterns of the sahityam are considered fine.
[4] The neraval is one of the features in the extempore improvisation aspect (Manodharma Sangita) of Carnatic music, and is intended to highlight the Raga bhava effectively.