Realism is an approach to art in which subjects are depicted in as straightforward a manner as possible, without idealizing them and without following rules of formal artistic theory.
The earliest Realist work began to appear in the 18th century, in a reaction to the excesses of Romanticism and Neoclassicism. This is evident in John Singleton Copley's paintings, and some of the works of Goya. But the great Realist era was the middle of the 19th century, as artists became disillusioned with the artifice of the Salons and the influence of the Academies.
Realism came closest to being an organized movement in France, inspiring artists such as Camille Corot, Jean-Francois Millet and the Barbizon School of landscape painters.
Besides Copley, American Realists included the painters Thomas Eakins, and Henry Ossawa Tanner, both of whom studied in France.
French Realism was a guiding influence on the philosophy of the Impressionists. The Ashcan School artists, the American Scene painters, and, much later, on the Contemporary Realists are all following the American Realist tradition.