A group of French naturalist painters, their approach to painting, beginning in the 1830s, opened the door to Plein-Air Painting, Impressionism and Social Realism. Barbizon School painters were based in the village of Barbizon, France on the outskirts of the Forest of Fontainebleau. Most were landscape painters who expressed fascination with changing seasons, changing times of day and the effects of light on the landscape. Barbizon artists had no agreed-upon style, but were revolutionary because of their commitment to portraying nature as a worthwhile subject in its own right rather than something that was so remote that it could only be expressed through romanticized and sublime images. In other words, nature was something that could be experienced personally and painted subjectively and not just romantically or philosophically. Barbizon School painters often included toiling peasants in their landscapes---persons who had little time or inclination towards 'contemplation' of nature. This approach was also revolutionary in prevailing approaches to fine art, which showed preferences for genteel subjects such as aristocrats basking in the beauty of their surroundings. Barbizon artists are considered the first "plein-air" painters, those who painted directly in the outdoors rather than completing their scenes in studios from sketches. Chief among the original French Barbizon painters were Camille Corot, Francois Millet, Theodore Rousseau, and Charles Daubigny. American painters much influenced by the Barbizon School were George Inness, Homer Martin, Alexander Wyant, William Morris Hunt aand Wyatt Eaton. Eaton and Hunt lived near Millet at Barbizon. Sources: "The Britannica Encyclopedia of American Art"; Kimberley Reynolds, "Illustrated Dictionary of Art Terms"
Associations may be by subject, geography, school, style, etc.