Abstract Expressionism is a form of art in which the artist expresses himself purely through the use of form and color. It is a form of non-representational, or non-objective, art, which means that there are no concrete objects represented. What appears to be accidental in this work is actually highly planned. Often, the expressive method of painting was considered as important as the work of art itself. In part, Abstract Expressionism was a reaction to the representational power of photography. Now considered to be the first American artistic movement of worldwide importance, the term was originally used to describe the work of Arshile Gorky, Willem de Kooning, and Jackson Pollock. The movement can be broadly divided into two groups: Action Painting, typified by artists such as Pollock, de Kooning, Franz Joseph Kline, and Philip Guston, put the focus on the physical action involved in painting; Color Field Painting, practiced by Mark Rothko and Kenneth Noland, among others, was primarily concerned with exploring the effect of pure color on a canvas.