Musical theatre is a form of theatrical performance that combines songs, spoken dialoue, acting, and dance. The story and emotional content of a musical – humor, pathos, love, anger – are communicated through the words, music, movement and technical aspects of the entertainment as an integrated whole. Although musical theatre overlaps with other theatrical forms like opera and dance, it may be distinguished by the equal importance given to the music as compared with the dialogue, movement and other elements. Since the early 20th century, musical theatre stage works have generally been called, simply, musicals.
Since the 20th century, the "book musical" has been defined as a musical play where songs and dances are fully integrated into a well-made story with serious dramatic goals that is able to evoke genuine emotions other than laughter. The three main components of a book musical are its music, lyrics and book. The book or script of a musical refers to the story, character development, and dramatic structure, including the spoken dialogue and stage directions, but it can also refer to the dialogue and lyrics together, which are sometimes referred to as the libretto (Italian for “little book”). The music and lyrics together form the score of a musical but the interpretation of a musical by its creative team heavily influences the way in which a musical is presented. That team includes a director, musical director, usually a choreographer and sometimes an orchestrator. A musical's production is also creatively characterized by technical aspects, such as set design, costumes, stage properties (props), lighting and sound, which generally change from the original production to succeeding productions.
