Graffiti (also known as tagging) occurs most in large cities and is generally assumed to be closely related to gang activities. Presumably gang members will draw their respective symbols on other people's walls, park benches, etc. in order to mark off their territory and warn away members of other gangs. However, this type of graffiti tends to be relatively small, to the point, and is rarely elaborate.

Tagging is more often done for personal reasons. There is good reason for this: many urban youths feel that they cannot claim ownership of anything. Their housing may be a government-sponsored project, their transportation is public trains and buses, their schools are publicly funded and uniformly terrible, their clothing bears one of several different famous brand names, their entertainment is the mind-numbing pap of pop media, their personal lives are most likely filled with instability at home, uncertainty with friends, boredom and frustration at school, and varying states of mortal danger just about everywhere else.

Thus is it that if a young person can get their hands on a good marker or a can of spray paint, they will sneak off to an unobserved blank patch on a wall, highway embankment, street sign, or other handy urban surface, and scrawl something that more or less gets across the message:

I was here! And you had better be impressed!

Graffiti in bathrooms

By far the most common type of tags are those written on the walls of bathrooms. These vary from the personal, such as "Ted sat here" and "Jenna is a tart" to the general, such as "Life stinks" and "If poop could fly, this place would be an airport!" Bathroom taggers generally tend not to thrill the viewer with their wit or artistic skill. Occasionally, especially in public-school bathrooms, conversations between rivals will be carried out on the walls of bathroom stalls. These can make entertaining, if crude, reading for those not involved. The reason bathroom stall tags are so common, if not universal, is that they present the would-be tagger with the irrestible combination of privacy and publicity; of the promise of an audience combined with the certainty of not being caught. The vandal can then further confuse matters by affixing the poster in an unrelated place, such as in the hallway of a public school. This can be especially funny if the city in which one lives starts up an anti-drug campaign featuring posters that say "Are you waiting for your kids to talk to YOU about pot?"

Graffiti on public transportation

Public transit taggers are a bit bolder than bathroom stall taggers and tend to be more ambitiouus. Most often a public transit tagger will use some sharp object (penknife, key, shard of broken glass) to scratch his name or nickname on a window. Transit taggers also frequently deface advertisements with markers or stickers, the latter having the appeal of easy application. Another common form of transit vandalism is the theft of advertisement posters, a feat rendered simple on public trains by the fact that any car other than the first one does not contain a conductor, and most passengers are too timid to offer any complaint.

Outdoor Graffiti

There are only two types of outdoor graffiti worth discussing at length: that meant to inspire artistic reverence, and that meant to inspire physical astonishment. Other types certainly exist, as anyone who has seen the witty tag VANDALISM IS WRONG will testify, but they are not as interesting or as widespread.

Artistic graffiti

This is the most socially acceptable form of graffiti in the average citizen's point of view: artistic tags are usually large, stylized cartoons representing some subject that the artist holds dear to heart. Most commonly an artist will write his nickname in multicolored, curving block letters of a style unique to the genre. Less often a subject that the artist considers to be of social interest will be represented, usually a portrait of youthful urban 'cool' featuring some representation of the artist themselves. Still more rarely a theme with sexual overtones will be treated: while impressive, graffiti of this nature tends to be frowned upon as inappropriate for public display.

Physically impossible graffiti

Everyone in the habit of driving along highways is familiar with this kind of tagging. Invariably these tags are in places that are virtually impossible to get to without breaking one's neck: on overpasses, halfway down sheer retaining walls, on billboards, on water towers, and so forth. These are meant to impress the viewer with sentiments such as "How in blazes did those kids get up there", as well as being designed to discourage removal. This is on the theory that if a bunch of urban youths have trouble clambering up to a spot in order to deface public property, then a bunch of urban officials will have an even harder time clambering up there to get rid of it.

Disclaimer

It must be noted of course that, despite the positive view taken on this subject by the author of this post (the author being an urban youth), illegal activities of any kind are certainly not condoned by the staff and organization of the Guide. Anyone who breaks the law, especially the Eleventh Commandment, deserves to pay for their crimes.