Musical Impressionism arose in late 19th century Europe as a reaction against Romantic excesses. It is characterized by suggestion and atmosphere over emotion. Impressionist composers favored short forms and explored scales like the whole tone scale. They introduced extended chord structures and major 7th chords. Key figures were Debussy and Ravel, and characteristics included irregular rhythm, avoidance of traditional harmony, use of unresolved dissonance, and scales like the whole tone scale.