Musical theatre originated from Greek theatre and other theatrical traditions incorporating music and dance to advance the plot and develop characters. A musical typically has music, lyrics, and a book (dialogue) that are integrated to tell a story. Key components include opening and closing numbers to set the tone and leave an impression, the "I want" song revealing character motivations, the act 1 closer hooking audiences for intermission, the 11 o'clock number energizing viewers in act 2, and song types like ballads and comedy numbers. Modern musicals come in various styles like book, rock, concept, jukebox, movie, and mega musicals utilizing different sources and production elements.