Theatre is one of the greatest forms of entertainment. Originating from the Ancient Greek Drama, theatre often incorporates actors and dancers as live performers, with stage props and occasionally musicians for the desired effect. Actors may stick to a pre-written script or more modern theatre groups such as Punch-Drunk use an interactive experience with the audience which can change the course of the theatre. Musical theatre uses songs from musicals, and a full orchestra with much of the plot being sung by the performers. Types of theatre include Roman theatre, Sanskrit theatre, Chinese theatre and Post-Classical Theatre such as works in the West End Theatre.