The Roaring Twenties, sometimes stylized as Roarin' 20s, refers to the 1920s decade in music and fashion, as it happened in Western society and Western culture. It was a period of economic prosperity with a distinctive cultural edge in the United States and Europe, particularly in major cities such as Berlin, Buenos Aires, Chicago, London, Los Angeles, Mexico City, New York City, Paris, and Sydney. In France, the decade was known as the années folles ("crazy years"), emphasizing the era's social, artistic and cultural dynamism. Jazz blossomed, the flapper redefined the modern look for British and American women, and Art Deco peaked. In the wake of the military mobilization of World War I and the Spanish flu, President Warren G. Harding "brought back normalcy" to the United States.

The social and cultural features known as the Roaring Twenties began in leading metropolitan centres and spread widely in the aftermath of World War I. The spirit of the Roaring Twenties was marked by a general feeling of novelty associated with modernity and a break with tradition, through modern technology such as automobiles, moving pictures, and radio, bringing "modernity" to a large part of the population. Formal decorative frills were shed in favour of practicality in both daily life and architecture. At the same time, jazz and dancing rose in popularity, in opposition to the mood of World War I. As such, the period often is referred to as the Jazz Age.

The 20s decade saw the large-scale development and use of automobiles, telephones, films, radio, and electrical appliances in the lives of millions in the Western world. Aviation soon became a business. Nations saw rapid industrial and economic growth, accelerated consumer demand, and introduced significant new trends in lifestyle and culture. The media, funded by the new industry of mass-market advertising driving consumer demand, focused on celebrities, especially sports heroes and movie stars, as cities rooted for their home teams and filled the new palatial cinemas and gigantic sports stadiums. In many major democratic states, women won the right to vote.