Street art is a phenomenon and subculture movement that reaches from the darkest urban backstreets to the most glamorous international art fairs. Despite having earned a place in the canon of twentieth-century art history, its qualifications are often disputed by both the art establishment and practitioners themselves, all concerned with notions of authenticity. This book examines how street art evolved from its origins in the 1970s New York graffiti scene to embrace many new materials, styles and techniques.