Wassily Kandinsky, 1912. Pure-abstraction breakthrough — one of the first canvases without identifiable subjects. Guggenheim, New York.
From Wikipedia
Improvisation or improvization is the activity of making or doing something not planned beforehand, using whatever can be found. The origin of the word itself is in the Latin "improvisus", which literally means un-foreseen. Improvisation in the performing arts is a very spontaneous performance without specific or scripted preparation. The skills of improvisation can apply to many different faculties across all artistic, scientific, physical, cognitive, academic, and non-academic disciplines; see Applied improvisation.