Short answers, pulled from the story.
Abstract art uses shape, form, color, and line to create compositions independent of visual references. It emerged as a departure from centuries of art history that relied on perspective to mimic reality around 1912 with works like Amorpha, Fugue en deux couleurs.
James McNeill Whistler painted Nocturne in Black and Gold: The Falling Rocket in 1874. He placed greater emphasis on visual sensation than the depiction of physical objects.
Henri Matisse and Georges Braque revolutionized the Paris art world at the beginning of the 20th century. They created wild, multi-colored landscapes that critics called Fauvism.
Walter Gropius founded the Bauhaus school at Weimar, Germany in 1919. The school moved to Dessau in 1925 before closing in 1932 as the Nazi party gained control.
Mark Rothko, born in Russia, dissolved his strongly surrealist imagery into powerful color compositions of the early 1950s. His work contributed to the main movements hosted by New York by the early 1940s including expressionism and abstraction.