Graffiti redirects here. For Wikivoyage's graffiti wall, see Wikivoyage:Graffiti wall Murals and graffiti are frequently encountered in urban environments.
As long as mankind has been able to paint, people have been drawing and scribbling on surfaces. The oldest versions of these are thousands of years old, found inside caves and sometimes even listed as UNESCO World Heritage site. Later on, especially churches and other religious buildings were decorated with pictures, especially on the inside. Some cities employ murals for political propaganda or advertising while others hope to take advantage of a "code of honor" that some graffiti sprayers feel bound by, not to spray on the work of another. Regardless of the reason, such murals can be beautiful and interesting to look at in their own right.
Unwanted murals or scribbles are known as graffiti. While graffiti is far from being only a modern phenomenon, most people probably associate it with youth vandalizing public and private property using spray paint. However, nowadays there are established graffiti artists, graffiti events and "legal" walls. Graffiti paintings in this context often resemble artworks rather than illegible tags. In times and at places when literacy was widespread, graffiti would often include identifiable words or even consist entirely of words. The best known modern example are perhaps the more ephemeral scribblings on the walls of public toilet stalls. As such graffiti are not much "filtered" by laws or the wishes of the ruling classes, they can - if preserved - give glimpses into the life of ordinary people in bygone times. Ancient Roman graffiti (for example those found in Pompeii) in particular provide insights into pronunciation (through their misspellings) as well as the mood of the times and the sometimes crude humor of the "common people".
Sometimes notable graffiti and murals are used by street gangs to mark their "territory". Going on a photo hunt for such artworks, particularly without someone familiar with the area, can be extremely dangerous.