Street art is a visual art created in public locations, usually unsanctioned artwork executed outside of the context of traditional art venues. Other terms for this type of art include "independent public art", "post-graffiti", and "neo-graffiti", and is closely related with urban and guerrilla art.
What is so cool about street art is that it can be playful in nature or it can also be political. The image to the left shows a clearly political message whereas the image to the right has a more playful approach. Both however, use the objects found on the wall to their advantage in getting the message across.
"Art is an evolutionary act. The shape of art and its role in society is constantly changing. At no point is art static. There are no rules." -Raymond Salvatore Harmon, BOMB: A Manifesto of Art Terrorism