In some musical genres, such as jazz and blues, even more freedom
is given to the performer to engage in improvisation on a basic melodic,
harmonic, or rhythmic framework. The greatest latitude is given to
the performer in a style of performing called free improvisation,
which is material that is spontaneously thought of (imagined)
while being performed, not preconceived.
According to the analysis of Georgiana Costescu, improvised
music usually follows stylistic or genre conventions
and even fully composed includes some freely chosen material.
Composition does not always mean the use of notation,
or the known sole authorship of one individual.