Some people consider graffiti, or some graffiti, an art form. Others do not.
The practices of graffiti and of considering graffiti as art are generally related to a sub-culture that rebels against extant societal authorities, or against authority as such. Graffiti art is considered one of the 5 elements of the Hip Hop Culture. Graffiti is characterized by brief quotations and intricate "tags" or encoded signatures which may be a name of the artist (alternatively described as a "writer") or a group of graffiti writers which the artist may associate alternatively described as a "crew". Graffiti art should NOT to be confused with "gang graffiti," the two have nothing in common, other than they are both done on walls. The purpose of graffiti art is self-expression and creativity, and may involve highly stylized letter forms, drawn with markers, or cryptic and colorful spraypaint murals on walls, and buildings, and even freight trains. Graffiti artists strive to improve their art, which is constantly changing and progressing. Gang graffiti, on the other hand, is usually limited to a gang's neighborhood, and serves to mark their territorial boundaries, it has no artistic intent.
Graffiti is subject to different societal pressures from popularly-recognized art forms, since graffiti appears on walls, freeways, buildings, trains or any accessible surfaces that are not owned by, or under the control of the person who applies the graffiti. So graffiti encorporates elements rarely seen elsewhere. Spray paint is commonly used, and the organizational structure of the art is sometimes influenced by the need to apply the art quickly before it is noticed by authorities. Although many cities, have set aside particular legal walls or areas, exclusively for use by graffiti artists. This encourages the artist to take their time and produce great art, without worry of being caught or arrested.
Jean-Michel Basquiat is an example of a graffiti artist.