Graffiti is the action of painting and writing on surfaces, usually outside walls and sidewalks, without the permission of the owner. The Vandals are famous for their graffiti (giving us the word vandalism). The Romans carved graffiti into both their own walls and monuments and for instance Egyptian ones. On the other hand Viking graffiti can be found in Rome. Many times in history graffiti was used as form of fight with opponents (see Orange Alternative for example). The Irish had their own inscriptive language called Ogham.
According to some, graffiti has evolved into a (still mostly illegal) art form of its own, with a modern history, master practitioners, categories of style, etc. Others regard it as simply an unwanted nuisance. Graffiti is one of the elements of the culture surrounding rap music.
Note: Graffiti is the plural of graffito, but the singular form is rarely heard.
To remove graffiti, high pressure cleaning can be used; it can also be painted over or as a prevention, a special formulated anti-graffiti coating may be applied to the surface of high risk areas.
Frescos and murals are art forms which involve leaving images and writing on wall surfaces. Like the ancient cave wall paintings in France, they are not graffiti as they are created with the explicit permission (and usually support) of the owner of the walls.
In the 20th century famous graffiti were the words 'Kilroy was Here', and a face with only the eyes and a nose hanging over the wall saying "What No...?" (thing that lacked at the time) during the time of rationing. The character in the second example was known as Mr. Chad[?].
Famous graffiti artists :