GRAFFITO is strictly speaking, 'graffito' (or 'sgraffito') describes any design scratched through a layer of paint or other material, to reveal a different ground underneath. The plural 'graffiti' now describes unauthorised designs or words which are painted, sprayed, scratched, or scribbled onto walls or other publicly visible surfaces, sometimes by political activists, sometimes by vandals, and sometimes by those with highly sophisticated artistic and graphic skills.
See Basquiat; Dubuffet
Cumming, Robert (2001). Art: A Field Guide (p. 397). New York: Alfred A. Knopf