origin and main architects
This new style, originated in England, approximately in 1890, was implemented in Europe, mainly in Brussels and Paris until 1914, ending with the beginning of the First World War.

It presented regional and national differences in its aesthetics and the term used to designate it, depending on the forms developed.
In England it was called Modern Style, in Italy Stile Liberty, in Austria Sezessionsstil (“secession style”), in Germany Jugendstil (“young style”) and finally in Spain by Modernism. France and Belgium named it Art Nouveau (“new art”), the name of a store in Paris, opened in 1895, specialized in the sale of objects with innovative design.
Allied to each location was an artist emblematic of its forms: in Brussels, Victor Horta (1861-1947) with his whip lines and Henry van de Velde (1863-1957), in France the decorator architect Hector Guimard (1867-1942) , in Barcelona with Antoni Gaudí, in Vienna with Josef Hoffmann, in Turin and Constantinople with Raimondo D’Aronco and in Glasgow with Rennie Mackintosh.
decorative arts

Although architecture is the greatest art here, the decorative arts were very important, marking an aesthetic favored by functional and beautiful pieces and a synthesis of all the arts with their integration into everyday life. The decorating architects of the projects argued that no object was too banal and deserved to have a detailed creation, whether it be a lamp, a piece of furniture, a stained glass window, a handle, a handrail, a wallpaper or a jug. Everything contributed to a total art, demonstrating an excessive concern for the minimum detail of the ornament, taking care of the interiors with the same rigor given to the edification.

Wall paper by John Henry Dearle para William Morris & Co. 1897
https://pt.wikipedia.org/wiki/Arts_%26_crafts#/media/File:Artichoke_wallpaper_Morris_and_Co_J_H_Dearle.jpg
This concept can be considered an influence caused by William Morris (1834-1896), the founder of “Arts and Crafts” in the nineteenth century in England, in which his architects and designers were in favor of handicrafts and nature lovers.
The art nouveau artists soon realized that the machines could not be defeated because of their advantages and allied to them, creating pieces suitable for industrial production, reducing prices.

Casa Batló, Barcelona
They rejected academicism and tried to create a completely new art, freeing artists from eclecticism and from any stylistic reference to the past. Examples include works such as Casa Batllò and Casa Milà, both on Passeig de Gràcia in Barcelona, the work of the most eccentric architect of this style: Antoni Gaudí.