Short answers, pulled from the story.
The British art critic Roger Fry invented the term Post-Impressionism in 1906 to describe a group of French painters. The term was first used in print by critic Frank Rutter in October 1910, three weeks before Fry organized his famous exhibition Manet and the Post-Impressionists.
The artists who came to be known as Post-Impressionists include Paul Cézanne, Paul Gauguin, Vincent van Gogh, and Georges Seurat. These painters never met to declare a new style nor did they agree on what their art should achieve.
The movement emerged from the last Impressionist exhibition in 1886 and lasted until the birth of Fauvism around 1905. The movement came to an end with the outbreak of World War I in 1914, which signaled a major break in European cultural history.
Georges Seurat developed a technique called pointillism that relied on the systematic application of tiny dots of pure color. He believed that the chaotic mixing of colors on a palette was inferior to the optical mixing that occurred within the viewer's eye, a theory he called Divisionism.
Vincent van Gogh used vibrant color and conspicuous brushstrokes to convey his feelings and his state of mind, transforming the canvas into a mirror of his inner turmoil. He did not paint what he saw, but what he felt, using thick impasto and swirling lines to create a sense of movement and emotion.
The Post-Impressionist movement spread to other countries including Canada, England, Germany, and Eastern Europe. In Canada, artists like Randolph Hewton, A. Y. Jackson, and John Lyman adopted the style, while in Germany, Paul Baum and Carl Schmitz-Pleis provided the decisive impetus for the movement.