Abstract Expressionism was a post-World War II art movement developed in New York in the 1940s. It involved expressing oneself purely through form and color, combining emotional intensity with anti-figurative styles. The movement is divided into Action Painting, which stresses physical painting action and broad gestures, and Color Field Painting, which explores the effects of pure color overlapping on huge canvases. Key artists included Jackson Pollock, Willem de Kooning, and Mark Rothko.