Graffiti is a part of what is now known as urban street art. Street art forms involve graffiti and spray paint, and yet the most successful graffiti does more than just show the name or word of the person who wrote them. Some graffiti is very skillfully done and it is now known that even graffiti has its rules.
Like any other good art, good graffiti relate to context and material and cause the viewer to think and evaluate their circumstances.
Graffiti has its own realm within the art world and some even play on the architectural forms it is painted on, even giving the effect of 3 dimensions. Graffiti has the ability to create the illusion of depth and complexity on a large two dimension a public surface.
Some street art is extremely straight forward, while other has a social message, still other artists actually clean public areas with their graffiti, which means that graffiti can be a wonderful way for an artist to express himself, and not necessarily express pure vandalism.
True, graffiti probably did start as a movement to deface and damage public buildings, but today we can see several examples of artists who have taken it one step further, and even help express the views of society and in places beautify instead of vandalize.