The word "abstract expressionism" describes the new directions taken in abstract painting by American artists in the 1940s and 1950s. Often, its distinguishing features are the appearance of spontaneity and the use of expressive brushstrokes or mark-making.

The abstract expressionists, who did much of their work in New York City, are known as the New York school. This moniker alludes to the artists' intention to create abstract works that generate strong feelings in the viewer. Both the surrealist belief that art should emerge from the subconscious and the automatism of artist Joan Miró served as inspiration.

There were two primary schools of thought within abstract expressionism: the action painters, who used aggressive brushwork, and the color field painters, who painted vast swathes of a single hue.

Jackson Pollock and Willem de Kooning spearheaded the action painting movement, emphasizing improvisation and broad brushes for making expressive, sweeping strokes. Famously, Pollock would lay his canvas on the floor and dance about it, dripping paint from the can or dragging it behind him on the floor with a brush or a stick. The action painters used this method to express their inner sensations visually.

Artists Mark Rothko, Barnett Newman, and Clyfford Still comprised the second set. They were preoccupied with myth and religion, and their paintings, which feature spare compositions and broad strokes of color, are meant to inspire a meditative state of mind in the beholder. "Instead of constructing cathedrals out of Christ, man, or "life," Barnett Newmann said in a 1948 article, "we are making it out of ourselves, out of our sentiments." Around 1960, artists began using vast expanses of uniform flat color to create a new painting style called color field painting.