Pop art emerged in the 1950s and spread worldwide, challenging the established concept of "fine art". It was inspired by popular culture and mass media imagery, using bright colors and flat, recognizable images from advertisements, comics, and celebrity portraits. Some of the seminal pop artists mentioned include Andy Warhol, Roy Lichtenstein, Richard Hamilton, Claes Oldenburg, and Jasper Johns. Pop art eroded the distinction between high and low art and made art more accessible to the public.