A speakeasy, also called a blind pig or blind tiger, is an establishment that illegally sells alcoholic beverages. Such establishments came into prominence in the United States during the period known as Prohibition (1920–1933, longer in some states). During this time, the sale, manufacture, and transportation (bootlegging) of alcoholic beverages was illegal throughout the United States.

The term "speakeasy" might have originated in Pennsylvania in 1888, when the Brooks High-License Act raised the state's fee for a saloon license from $50 to $500. The number of licensed bars promptly plummeted, but some bars continued to operate illegally. Kate Hester had run a saloon for years in McKeesport, just outside of Pittsburgh. She refused to pay the new license fee and wanted to keep from drawing attention to her illegal business. When her customers got too rowdy, she would hush them by whispering, "Speak easy, boys! Speak easy!"

Unlicensed saloons in Pennsylvania are known as “speak-easies.”

Speakeasies were numerous and popular during the Prohibition years. Some of them were operated by people who were part of organized crime. Even though police and agents of the Bureau of Prohibition would often raid them and arrest their owners and patrons, they were so profitable that they continued to flourish.

Swing music, or simply swing, is a form of American music that developed in the early 1930s and became a distinctive style by 1935. Swing uses a strong rhythm section of double bass and drums as the anchor for a lead section of brass instruments such as trumpets and trombones, woodwinds including saxophones and clarinets, and sometimes stringed instruments such as violin and guitar, medium to fast tempos, and a "lilting" swing time rhythm.The name swing came from the phrase ‘swing feel’ where the emphasis is on the off–beat or weaker pulse in the music ( unlike classic music). Swing bands usually featured soloists who would improvise on the melody over the arrangement. The danceable swing style of big bands and bandleaders such as Benny Goodman and Count Basie was the dominant form of American popular music from 1935 to 1945, a period known as the Swing Era.

The verb "to swing" is also used as a term of praise for playing that has a strong rhythmic "groove" or drive.

The styles of jazz that were popular from the late teens through the late 1920s were usually played with rhythms with a two beat feel, and often attempted to reproduce the style of contrapuntal improvisation developed by the first generation of jazz musicians in New Orleans. In the late 1920s, however, larger ensembles using written arrangements became the norm, and a subtle stylistic shift took place in the rhythm, which developed a four beat feel with a smoothly syncopated style of playing the melody, while the rhythm section supported it with a steady four to the bar.