Abstract Expressionism is the term used for new forms of abstract art coming from American painters such as Jackson Pollock, Mark Rothko and Willem de Kooning in the 1940s and 1950s.

Image source: https://www.pinterest.it/pin/502573639648103475/
The Origins
One of the many paradoxes of Abstract Expressionism is that the origins of the movement can be traced back to the figurative painting of 1930s. Almost all the artists who would later become abstract artists in New York were influenced by the experience of the Great Depression. They became mature whilst painting in styles influenced by Regionalist movements.
and the
Image source: https://www.theartstory.org/movement/abstract-expressionism/
Abstract Painting Features
Abstract Expressionism is famous for large-scale works distant from traditional processes. While Abstract Expressionism is studied for its advancements in painting, its ideas had deep influence in many aspects of everyday life, including drawing and sculpture. Similarly, instead of having interest solely on finished works, these artists focused on the process. The shapes are employed in various ways to create a sensations of volume, and movement. These elements are fused into expressive patterns in order to depict real or supernatural phenomena.

Image source: https://www.wassilykandinsky.net/work-540.php
The Most Important Painters
Here are the names of the best known artists of this movement:
- Paul Klee: he was a Swiss artist famous for his large body of works influenced by cubism, expressionism and surrealism;
- Piet Mondrian: he was a Dutch painter, leading figure in the De Stijl movement, that focused on simple forms and colurs,
- Hans Arp: he was one of the main artists of Dada in Zurich;
- Malevich: Russian artist that will found Suprematism.
- Robert Delaunay: he was the author of the “Sun and the Moon” (1912), “Sun n. 2” (1912-1913), “The City” (1910).

Image source: https://www.guggenheim.org/artwork/1021
Info source: https://www.britannica.com/art/abstract-art