Painting, sculpture, and other artforms can be divided into the categories of representational (sometimes also called figurative art although it doesn’t always contain figures), abstract and nonrepresentational art. Representational art describes artworks—particularly paintings and sculptures–that are clearly derived from real object sources, and therefore are by definition representing something with strong visual references to the real world. Most, but not all, abstract art is based on imagery from the real world. The most “extreme” form of abstract art is not connected to the visible world and is known as nonrepresentational.
Representational art or figurative art represents objects or events in the real world, usually looking easily recognizable. For example, a painting of a cat looks very much like a cat– it’s quite obvious what the artist is depicting.
Romanticism, Impressionism, and Expressionism contributed to the emergence of abstract art in the nineteenth century as artists became less interested in depicting things exactly like they really exist. Abstract art exists on a continuum, from somewhat realistic representational work, to work that is not based on anything visible from the real world. Even representational work is abstracted to some degree; entirely realistic art is elusive.
Work that does not depict anything from the real world (figures, landscapes, animals, etc.) is called nonrepresentational. Nonrepresentational art may simply depict shapes, colors, lines, etc., but may also express things that are not visible– emotions or feelings for example.