Forms off graffiti and street art have been round since the year AD79 with images from the volcanic eruption of Mount Vesuvius in Pompeii, it shows people have carved images into the walls explaining the story of the eruption. It's come along way since then evolving into a debated 'art' form, a way for people to express themselves publicly, a crime. It has evolved from many things a lot of them political and people wanting rights, a handful of people make this public on walls and building's basically saying FUCK YOU to society and the government so all can see. Here's a few good examples of this.

Dalismo-

Banksy -

Marc Ecko tags air force one-

Even adverts are stealing graffiti designs and ideas, here's a Corsa advert from 2011-

Here's an amazing piece of graffiti i was shown in college a few years back i think this is where the car companies got the idea from it's a brilliant and very strange piece thats 7 minutes in length. It took ages to make.