This USPS stamp illustrates Pollock's drip technique.
Abstract expressionism was an American post-World War II art movement. It was the first specifically American movement to achieve worldwide influence and also the one that put New York City at the center of the art world, a role formerly filled by Paris.
The term was first applied to American art in 1946 by the critic Robert Coates.
Technically, its most important predecessor is often said to be surrealism, with its emphasis on spontaneous, automatic or subconscious creation. Jackson Pollock's dripping paint onto a canvas laid on the floor is a technique that has its roots in the work of Max Ernst.
The movement gets its name because it is seen as combining the emotional intensity and self-expression of the German Expressionists with the anti-figurative aesthetic of the European abstract schools such as Futurism, the Bauhaus and Synthetic Cubism. Additionally, it has an image of being rebellious, anarchic, highly idiosyncratic and, some feel, rather nihilistic.
In practice, the term is applied to any number of artists working in New York who had quite different styles, and even applied to work which is not especially abstract nor expressionist. Pollock's energetic "action paintings", with their "busy" feel, are very different both technically and aesthetically to the rather violent and grotesque Women series of Willem de Kooning (which is not particularly abstract) and to the serenely shimmering blocks of colour in Mark Rothko's work (which does not seem particularly expressionist), yet all three are classified as abstract expressionists.
That said, abstract expressionist paintings do tend to share certain definite characteristics, such as a fondness for large canvases, an emphasis on the canvas's inherent flatness, and an "all-over" approach, in which all areas of the canvas are treated with equal importance (as opposed to the center being of more interest than the edges, for example).
As the first truly original school of painting in America, abstract expressionism demonstrated the vitality and creativity of the country in the post-war years, as well as its need (or ability) to develop an aesthetic sense that was not constrained by the European standards of beauty.
The style attracted the attention, in the early 1950s, of the CIA. They saw it as a means of promoting the idea that the USA was a haven of free thought and free markets, and also as a means of challenging both the socialist realist styles prevelant in communist nations, and the dominance of the European art markets. The books by Frances Stonor Saunders (The Cultural Cold War - The CIA and the World of Arts and Letters) details how the CIA went about financing and organising the promotion of American abstract expressionists, via the Congress for Cultural Freedom from 1950-1967.
Articles on two leading abstract expressionists Jackson Pollock (http://www.terraingallery.org/Jackson-Pollock-Ambition-DK.html) and Philip Guston (http://www.aestheticrealism.org/Philip_Guston/Philip_Guston.html), by American artist Dorothy Koppelman, relating their art to their lives from the Aesthetic Realism point of view, can be seen on the Terrain Gallery (http://www.terraingallery.org/Art-Talks-Archive.html) Web site.
Canadian artist, Jean-Paul Riopelle (1923-2002), helped introduce abstract impressionism to Paris in the 1950s.
By the 1960s, the movement had lost most of its impact, and was no longer so influential. Movements which were direct responses to, and rebellions against, abstract expressionism had begun, such as pop art and minimalism. However, many painters, such as Fuller Potter, who had produced abstract expressionist work continued to work in that style for many years afterwards extending and expanding its visual and philosophical implications.
Abstract expressionism's main representatives were: