Abstract Expressionism was an influential art movement of the mid-20th century that emphasized spontaneity and the personal emotional experience of the artist. There were two major types: action painting, exemplified by Jackson Pollock's drip technique, and color field painting, where artists like Hans Hoffman and Richard Diebenkorn used large areas of color to create a sense of depth. Jackson Pollock was a seminal action painter and is considered the "father" of Abstract Expressionism, which helped establish American art on the global stage for the first time.