Graffiti has always been a big interest of mine, as I am an artist and I find the idea of stylized writing or "flow" very intriguing. Just like a rapper must go with the flow in his lyrics, a graffiti artist must create a visual piece which fits together as a whole. Graffiti styles often have very complex interwoven characters, colors, styles and shapes.
Urban graffiti is a form of expression which came from the Bronx and quickly spread throughout the world. I think most people see graffiti as a form of decay, however I think in many ways it serves as inspiration for other graffiti writers, DJ's or MC's. Originally, writing your 'tag' on the wall was a way to increase street rep and fame, and that quickly gave birth to a whole array of styles of graffiti. Afterwards it became a way to express your inner style in a very diverse way, to allow the listener to groove on what they hear (the music) and what they see (the graffiti).
I think in a similar way that MC's try to outdo eachother in hip-hop battles, graffiti artists try to outdo each other in terms of style. Tags are often painted over previous ones, and I constantly see more complex styles emerging all the time.

