Street Graffiti

Graffiti and graffito are from the Italian word graffiato ("scratched"). "Graffiti" is applied in art history to works of art produced by scratching a design into a surface. A related term is "graffito", or "sgrafitto," which involves scratching through one layer of pigment to reveal another beneath it. This technique was primarily used by potters who would glaze their wares and then scratch a design into it. In ancient times graffiti was carved on walls with a sharp object, although sometimes chalk or coal were used. The word originates from Greek γράφειν — graphein — meaning "to write."
History
The term graffiti referred to the inscriptions, figure drawings, etc., found on the walls of ancient sepulchers or ruins, as in the Catacombs of Rome or at Pompeii. Usage of the word has evolved to include any graphics applied to surfaces in a manner that constitutes vandalism.