One of the most common forms of graffiti is tagging, or the act of stylizing your unique name or logo. Tagging began in Philadelphia and New York City and has expanded worldwide. Spray painting public property or the property of others without their consent can be considered vandalism, and the "tagger" may be subject to arrest and prosecution for the criminal act. Whether legal or not, the hip hop culture considers tagging buildings, trains, bridges and other structures as visual art, and consider the tags as part of a complex symbol system with its own social codes and subculture rules. Such art is in some cases now subject to federal protection in the US, making its erasure illegal.