1. “Camille Pissaro “Le Pont Neuf”
Impressionism
“Camille Pissaro “Le Pont Neuf”
1901
The term 'Impressionist' was first used as an insult in response to an exhibition of new paintings in Paris in A diverse group of painters, rejected by the art establishment, defiantly set up their own exhibition. They included Monet, Renoir, Pissarro, and Degas.
What characterises Impressionism for most people nowadays, is both the subject matter and the technique. Landscapes, and scenes from modern urban and suburban life painted in bright, pure colours are typical. Impressionists often began (and sometimes completed) their paintings outdoors rather in a studio. Their rapidly applied brushstrokes are often visible. 

2. Claude Monet “The Cliff at Fecamp” 1881
En Plein Air
Thick and short brush strokes aim top capture the essence of the subject and create an impression, rather than delving on its details. The painting style is often referred to as impasto.
Colours are juxtaposed side-by-side with as few mixing as possible to create a vibrant colour temperature where the colours mix in the eye of the beholder. On the other hand, greys and dark colours are produced by mixing complementary colours.  Pure impressionism avoids the use of black
Sharp edges are rare. Instead, impressionist works have soft subject edges where wet paint is applied into wet paint of another colour in successive strokes to produce soft edges between colour transitions.
Impressionist paintings do not use transparent or thin paint films (glazes) that realist artists employee to produce effects. Impressionist surfaces are often opaque.
Natural light highlighted with close attention to the reflection of colours from one object to another.  In morning scenes, shadows are boldly painted with the blue of the sky or whatever the colour of the objected where they are cast, providing a sense of freshness not represented in earlier realist styles. Blue shadows on snow influenced this technique called diffused reflection that has become a hallmark of impressionist paintings.
Claude Monet “The Cliff at Fecamp” 1881

3. “The waterlilly Pond” “Impression Sunrise” 1899 1872
Claude Monet

4. Camille Pissaro “Kitchen Garden at L'Hermitage, Pontoise ”
Camille Pissaro “Kitchen Garden at L'Hermitage, Pontoise ” “The Vegetable Garden with Trees in Blossom

5. Auguste Renoir. “La Grenouillère”. “Bal du moulin de la Galette”. 1869

6. Vincent Van Gogh “Self Portrait” “Starry Night” 1886-1889 1889

7. Berthe Morisot “Summer Day” “Chasing Butterflies” 1879 1874

8. Claude Monet “Artist Garden at Vetheuil”