Neil Sorrell

Improvisation is among the most widely practised yet least understood methods of music-making. Its impermanence and resistance to accurate preservation make it one of the most difficult of topics to research and document.
The word itself poses all kinds of problems, not only because of its extensive and vague applications to music, but also because of its usage in everyday speech, conveying something that is insufficiently prepared and of no lasting value (for example ‘an improvised shelter’). …
Another major problem is the assumption that improvisation can be defined in an absolute, hence universal, way. Discussions therefore tend to begin with such a definition, but are almost immediately compelled to investigate improvisation within a particular culture and context. How far these detailed examinations relate to each other and to the central, common definition is not always made clear.