A salon is a government sponsored exhibition. Originally held in 1725 as the annual event of the French Academy of Art (Académie des Beaux-Arts), the salons signaled what styles, subjects, or individuals were considered most admirable. Juries selected the works and then arranged them in floor-to-ceiling displays ("salon-style" galleries). For artists, the inclusion and location of one's painting could determine whether or not it was noticed by attendees or reviewed by journalists.
In 1863, the Salon of the Refused (Salon des Réfuses) was established to exhibit works rejected by the Salon jury, and the group later classified as Impressionists, had the first of their eight independent exhibitions in 1874. By the end of the 19th century, the importance of academies and conservative salon juries waned in favor of avant-garde movements and exhibitions of like-minded artists.
The Salon and The Royal Academy in the Nineteenth Century
Read Dr. Jason Rosenfeld's October 2004 essay in the Heilbrunn Timeline of Art History (The Metropolitan Museum of Art).
Courbet Dossier, Artistic Context
This web page contains brief histories of The Académie des Beaux-Arts, The Salon, Courbet and the Salon, Academic Painting, Romanticism, and Universal Exhibitions (Musée d'Orsay, 2006).