Impressionism

" The impressionist style of painting is characterized chiefly by concentration on the general impression produced by a scene or object and the use of unmixed primary colors and small strokes to simulate actual reflected light."

Taken from  http://www.ibiblio.org/wm/paint/glo/impressionism/

Impressionism came to be in the 1870's and 1880's.  It involved small, thin, yet visible brush strokes.  Early impressionists violated the rules of academic painting.  

In 1874 a group of artists known as the anonymous society of painters organized an exhibition in Paris that launched impressionism.  

After a while these seemingly casual paintings became widely acceptable.  

The Monet Family in Their Garden at Argenteuil, 1874
Édouard Manet (French, 1832–1883)
Oil on canvas

Here is an impression painting.  In 1860 Edouard Manet was Claude Monet's hero.  In 1874, they became friends.  

http://www.metmuseum.org/toah/works-of-art/1976.201.14