Graffiti and street art: two global art phenomenon of our current society. Cities worldwide are covered in letterings, posters, stickers or painted/sprayed characters. This leads to the point that cityscapes cannot be imagined without urban art anymore.This thesis aims to discuss the stages of development of urban art in the course of time. First of all there is a focus on the historical forms of graffiti on one hand and of street art on the other hand. Between the 14th and 18th century graffiti have been traits of the poor and homeless and had in the common opinion no artistically value. Graffiti did not evolve to a serious art form until 1960, when their popularity grew within the United States of America. American graffiti were solely born out of the desire to present the artist?s own name/nickname and in line with that its personality, in the public space. A subculture with a sternly hierarchy and strict rules was established, which is introduced in this thesis. Furthermore the different graffiti styles that emerged will also be discussed within this paper.Over time American graffiti became very famous, also throughout American boarders, which enabled graffiti-writers to gain access to the professional art network. A great number of artists started paying attention to this new art movement. Although they were not a part of the graffiti-culture, they realized the potential of art in the public space. Having their own work being present in the streets enabled them to show a huge amount of people their art at once. This constituted the birth of street art. This subculture will be also discussed in the thesis, as well as some famous street artists and their work.In this context graffiti-writer enabled the development of street art, since they recaptured the public space for art and the freedom of expression.