Jazz Guitar
Group Improvisation is the allowance made for degrees of disciplined expansion and contraction of a given theme. The big shapes are provided by the composer of the theme, for example, the basic melodic, harmonic and rhythmic components of a certain song. The rest is up to the participants to flesh out their own parts in correspondence with each other's interpretation at that moment in time. Most group activities have room for some degree of Group Improvisation. The nature of this expansion and contraction is determined by the composition and the way it has been presented by the composer or by the way the presiding group of participants is reinterpreting it.