The "Ashcan School" referred to a loosely connected group of artists in the early twentieth century in Philadelphia and New York. John Sloan, Everett Henri, and George Luks were among the prominent artists associated with the movement. The movement, while fairly loosely associated, was largely united through a devotion to presenting scenes of urban life in a gritty, realistic manner.

The Marilyn Diptych was created shortly after Marilyn Monroe's death in 1962. In order to create the work, Andy Warhol used only one publicity still of the actress, and repeated the image fifty times. Warhol used silk-screening, a process where a wooden stencil pushes ink-covered mesh onto a medium, to repeat the image. The left side of the diptych is painted over in bright, pastel colors, while the right side features only black and white images of the actress.

The abstract expressionists were a group of artists in post-World War II New York City who created large canvases of abstract forms with a focus on emotional elements. The artists actually used a variety of styles and approaches, from Jackson Pollack's drip paintings to the figural shapes of Willem de Kooning and Paul Klee and the color forms of Clyfford Still and Mark Rothko. The use of abstract painting was a profound departure in American art, in particular from the significant realism of artists such as Edward Hopper.

Roy Lichtenstein became famous in the 1960s through a series of large canvasses that were directly copied from comic books. Using comic book images as inspiration, Lichtenstein also applied a technique known as Ben-Day Dots, the stenciling of small dots that colored comic books in the era. Lichtenstein would continue to use the technique in his later career, when he was no longer directly adapting images from comic books.

A collage is constructed not as one image, but by compiling a variety of images into one larger piece. This can be done for a variety of reasons, including ironic juxtaposition, social commentary, or refreshing traditional imagery. Collages became more widely used in the twentieth century as various forms of media were brought into widespread use.

Jackson Pollack began his career as an expressionist painter, using representative shapes and traditional methods. Beginning in the late 40s, however, Pollack began using the technique of "drip painting," which involved laying the canvas on the floor and splattering liquid paint on it from above. This produced paintings that were extremely abstract, but vivid and emotional, which garnered Pollack worldwide acclaim.

Marcel Duchamp was a member of the global Dada movement, a school of artists from Zurich, Paris, Cologne, Berlin, and New York between 1916 and 1925. Kahlo, Ernst, and Miró were all members of the Surrealist movement, which occurred during the same era and employed a mixture of psychoanalysis, mysticism, and symbolism to reveal unconscious thoughts.

"Provenance" is exclusive to art, whereas "ancestry" applies to people and "record" is less specific; provenance is essential to prove the legitimacy and authenticity of both modern and older paintings. (This question is not limited to the scope of twentieth and twenty-first century art, but has arguably become more important in this period.)

Art Nouveau was an art style that surged to popularity in Europe and the US during the late 19th and early 20th centuries. Its forms and figures could be described as natural, organic, or flowing. Its general style was a very different from the bold, geometrical shapes of its successor, the Art Deco style.

The main subject of the painting is placed in front of a series of canvases, indicating the painting's setting is in an artist's studio. Being placed somewhat easily into such a setting indicates that the subject is an artist, with the exact nature of those canvases looking like the artist's work, indicating a self-portrait. Ernst Ludwig Kirchner frequently returned to self-portraits throughout his career, often with female models placed with him.

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