overture

In music, the opening piece of a concert or opera. It has two roles: settling the audience before the main music starts, and allowing the conductor and musicians to become acquainted with the acoustics of a concert auditorium. See also prelude.

The use of an overture in opera began during the 17th century; the ‘Italian’ overture consisting of two quick movements separated by a slow one, and the ‘French’ of a quick movement between two in slower tempo.