A dandy is a man who places particular importance upon physical appearance and personal grooming, refined language and leisurely hobbies; every activity pursued with apparent nonchalance. A dandy could be a self-made man in person and persona, who imitated an aristocratic style of life, despite his middle-class origin, birth, and background, especially in the Britain of the late-18th and early-19th centuries.

Early manifestations of dandyism were Le petit-maître (the Little Master) and the musky Muscadin ruffians of the middle-class Thermidorean reaction (1794–1795), but modern dandyism appeared in the stratified societies of Europe during the revolutionary period of the 1790s, especially in cultural centres such as London and in Paris. Socially, the dandy cultivated a persona of extreme cynical reserve to the degree that the Victorian novelist George Meredith defined such posed cynicism as "intellectual dandyism"; whereas the kinder Thomas Carlyle, in the novel Sartor Resartus (1831), dismissed the dandy as just "a clothes-wearing man"; and Honoré de Balzac in La fille aux yeux d'or (1835) chronicled the idle life of Henri de Marsay, a model French dandy done in by his obsessive Romanticism in pursuit of love, which included yielding to sexual passion and murderous jealousy.

In the metaphysical phase of dandyism, the poet Charles Baudelaire defined the dandy as a man who elevates æsthetics to a religion. That the dandy is an existential reproach of the conformity of the middle-class man, because "dandyism, in certain respects, comes close to spirituality and to stoicism" as an approach to living daily life. That "these beings, have no other status, but that of cultivating the idea of beauty in their own persons, of satisfying their passions, of feeling and thinking . . . [because] Dandyism is a form of Romanticism. Contrary to what many thoughtless people seem to believe, dandyism is not even an excessive delight in clothes and material elegance. For the perfect dandy, these [material] things are no more than the symbol of the aristocratic superiority of mind."

The linkage of clothing and political protest was a particularly English national characteristic in 18th-century Britain; the sociologic connotation is that dandyism was a reactionary protest against social equality, against the levelling effect of egalitarian principles, thus the dandy is nostalgic for feudal values and the ideals of the perfect gentleman and the autonomous aristocrat — men of self-made person and persona. Paradoxically, the social existence of the dandy required the gaze of spectators, an audience, and readers for their "successfully marketed lives" in the public sphere, as in the cases of the playwright Oscar Wilde and the poet Lord Byron, each of whom personified the two social roles of the dandy: (i) the dandy-as-writer, and (ii) the dandy-as-persona; each role a source of gossip and scandal, each man limited to entertaining high society.