Film of the 1920s marked an era of silent movies and new innovations that would allow viewers to not only see the actors, but hear them, too. Early movies featured in-theatre accompanyments to match the mood of the films, but the invention of the Movietone, in 1926, allowed sound to be recorded on film, and thus, a new generation of movies was born. The first of these movies was The Jazz Singer (1927), featured at the right, is considered a pivotal point in sound films, which were nicknamed "talkies."
Cinematic icons like Charlie Chaplin, who wrote and produced The Kid (1921), and Rudolph Valentino, who starred in The Sheik (1921), became wildly famous for their roles and were two of the first true "movie stars." In addition, cartoonist Walt Disney released The Karnival Kid (1929) and director D. W. Griffith gained a celebrity status with his movie Dream Street (1921) during this time period. The 1920s also saw the evolution of mega-film companies like Warner Bros. and Metro-Goldwyn-Mayer (MGM) Studios, who competed in sound-innovation progress and who could make the most profit.
The 1920s are noted as the time period when film really took off, becoming more available to the public and making great strides in quality and in sound synchronization.
If film was the bread of the 1920s, then theatre would be the butter. During this time, Broadway reached its peak in popularity. For the first time, black performers acted alongside white performers, and the emergence of Vaudeville, or Broadway performances mixed with jazz music, helped boost popularity of musical theatre.
Those who dominated the theatre scene included composer Cole Porter, actor Charles Gilpin, and producers Eva Le Gallienne and Oscar Hammerstein, who all contributed greatly to Broadway. Some of the most notable plays and musicals from this time period are The Emperor Jones (1920), What Price Glory?, and Desire Under the Elms.
Overall, the 1920s were the starting point for the huge successes that film and theatre would experience, and paved the way for future decades.
Sources: http://www.1920-30.com/movies/