Aestheticism (also known as the aesthetic movement) was an art movement in the late 19th century that valued the appearance of literature, music, fonts, and the arts over their functions. According to Aestheticism, art should be produced to be beautiful, rather than to teach a lesson, create a parallel, or perform another didactic purpose, a sentiment expressed in the slogan "art for art's sake." Aestheticism flourished, in the 1870s and 1880s, gaining prominence and the support of notable writers, such as Walter Pater and Oscar Wilde.

Aestheticism challenged the values of mainstream Victorian culture, as many Victorians believed that literature and art fulfilled important ethical roles. Writing in The Guardian, Fiona McCarthy states that "the aesthetic movement stood, in stark and sometimes shocking contrast, to the crass materialism of Britain, in the 19th century."

Aestheticism was named by the critic Walter Hamilton in The Aesthetic Movement in England, in 1882. By the 1890s, decadence, a term with origins in common with aestheticism, was in use, across Europe.

Aestheticism has its roots in German Romanticism. Though the term "aesthetic" derives from Greek, Alexander Gottlieb Baumgarten's Aesthetica (1750) made important use of it, in German, before Immanuel Kant incorporated it into his philosophy in the Critique of Judgment (1790). Kant, in turn, influenced Friedrich Schiller's Aesthetic Letters (1794) and his concept of art as Spiel (Play): "Man is never so serious as when he plays; man is wholly man only when he plays.” In the Letters, Schiller proclaimed salvation through art:

Man has lost his dignity, but Art has saved it and preserved it for him in expressive marbles. Truth still lives in fiction, and from the copy, the original will be restored.

These ideas were imported to the English-speaking world, largely through the efforts of Thomas Carlyle, whose Life of Friedrich Schiller (1825), Critical and Miscellaneous Essays and Sartor Resartus (1833–1834) introduced and advocated aestheticism while also, if not marking the earliest use of the word "aesthetic" in the English language, certainly popularising it. Ruth apRoberts declared him the "apostle of aesthetics in England, 1825–1827,” in recognition of his pioneering influence on the subsequent development of the aesthetic movement.

The British decadent writers were much influenced by the Oxford professor Walter Pater and his essays published during 1867–1868, in which he stated that one had to live life, intensely, and seek beauty. His text, Studies in the History of the Renaissance (1873), was very popular, among art-oriented young men of the late 19th century. Writers of the Decadent movement used the slogan "Art for Art's Sake" (L'art pour l'art), the origin of which is debated. Some claim that it was created by the philosopher Victor Cousin, although Angela Leighton notes that it was used by Benjamin Constant, as early as 1804, in the work On Form: Poetry, Aestheticism and the Legacy of a Word (2007). It is, generally, accepted to have been popularised by Théophile Gautier in France, who used the phrase to suggest that art and morality were separate.

The artists and writers of Aesthetic style tended to profess that the Arts should provide refined sensuous pleasure, rather than convey moral or sentimental messages. As a consequence, they did not accept John Ruskin, Matthew Arnold, and George MacDonald's conception of art as something moral or useful, "Art for truth's sake". Instead, they believed that Art did not have any didactic purpose; it only needed to be beautiful. The Aesthetes developed a cult of beauty, which they considered the basic factor of art. Life should copy Art, they asserted. They considered nature as crude and lacking in design, when compared to art. The main characteristics of the style were: suggestion rather than statement, sensuality, great use of symbols, and synaesthetic/Ideasthetic effects—that is, correspondence between words, colours and music. Music was used to establish mood.^{[citation needed]}