In the U.K., classical music is composed by individuals and written down. Indian music is based on certain sequences called ragas. When I perform live, 95% of the music is improvised: it never sounds the same twice.
Ah, 'Pather Panchali' was the most inspiring film that I wrote music for, and it was so spontaneously done. I saw the film, composed on the spot, along with myself and only four other musicians, and everything was done within 4-1/2 hours, I think an all-time record anywhere.