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.
C Monet, P-A Renoir, A Sisley, C Pissarro, Berthe Morisot, Mary Cassatt, G Caillebotte, E Degas, E Manet (for a short period), T Robinson. All French except the American Robinson. Cassatt, US-born,...
Manet was really the bridge between Realism and Impressionism. Edit: Claude Monet painted "Impression, soleil levant" in 1872 wich is the painting that first inspired the name of the Impressionist...
I think you mean a post-impressionist artist. This is a term applied to Vincent van Gogh and Paul Gauguin, because they came after and differed from the impressionists.