Musical theater is a form of theatrical performance that combines song, spoken dialogue, acting, and dance. The plot and emotional content of musicals – humor, pathos, love, anger – are conveyed through words, music, movement, and the technical aspects of entertainment as a whole. Although musical theater overlaps with other theatrical forms such as opera and dance, it can be distinguished in that music is given the same importance as dialogue, movement, and other elements. Since the early 20th century, stage works of musical theater have generally been referred to simply as musicals .

Although music has been part of dramatic performances since ancient times, modern Western musical theater emerged in the 19th century with many structural elements. elements established by the works of Gilbert and Sullivan in Britain and Harrigan and Hart in America. They were followed by numerous Edwardian musical comedies and musical theater works by American authors such as George M. Cohan at the turn of the 20th century. Princess Theatre musicals (1915-1918) and other clever shows such as Of Thee I Sing (1931) were artistic steps ahead of revues and other frothy early 20th century entertainment and led to such groundbreaking works as Show Boat (1927) and Oklahoma! (1943). Some of the most famous musicals of subsequent decades include West Side Story (1957), The Fantasticks (1960), Hair (1967), Chorus Line (1975), Les Miserables (1985), Phantom of the Opera (1986), Rent (1996), The Producers (2001), Wicked (2003) and Hamilton (2015).

The musicals have been performed all over the world. They can be presented at big venues such as the high-budget Broadway or West End in New York or London. Alternatively, musicals can be staged in smaller venues such as fringe Theater , Off-Broadway , Off-Off-Broadway , regional theater , or community theater , or touring . Musicals are often presented by amateur and school groups in churches, schools, and other venues. In addition to the United States and Great Britain, there are vibrant musical theater scenes in continental Europe, Asia, Australia, Canada, and Latin America.