This text depicts and explains the practices and processes of musical improvisation. Improvisation, by its nature, seems to resist interpretation or explanation. With contributions from 17 scientists and improvisers, the text offers a history of research related to improvisation and an overview of various approaches to the subject, ranging from cognitive studies to detailed musical analysis.

Different genres, such as Italian lyrical music, modal jazz, Indian classical music, Javanese gamelan, and African-American children's game songs are examined.