From Wikipedia-edited for size.
Art Nouveau is an international style of art, architecture and applied art, especially the decorative arts. The style was most popular between 1890 and 1910. It was a reaction against the academic art, eclecticism and historicism of 19th century architecture and decoration. It was often inspired by natural forms such as the sinuous curves of plants and flowers. Other characteristics of Art Nouveau were a sense of dynamism and movement, often given by asymmetry or whiplash lines, and the use of modern materials, particularly iron, glass, ceramics and later concrete, to create unusual forms and larger open spaces.
One major objective of Art Nouveau was to break down the traditional distinction between fine arts (especially painting and sculpture) and applied arts. It was most widely used in interior design, graphic arts, furniture, glass art, textiles, ceramics, jewelry and metal work. The style responded to leading 19-century theoreticians.
From Belgium and France, it spread to the rest of Europe, taking on different names and characteristics in each country. It often appeared not only in capitals, but also in rapidly growing cities that wanted to establish artistic identities (Turin and Palermo in Italy; Glasgow in Scotland; Munich and Darmstadt in Germany), as well as in center of independence movements (Helsinki in Finland, then part of the Russian Empire; Barcelona in Catalonia, Spain).
By 1910, Art Nouveau's influence was fading. It was replaced as the dominant European architectural and decorative style first by Art Deco and then by Modernism.