Overtures

Overture (from French ouverture, "opening") is a music instrumental introduction to a ballet, opera, or oratorio in the 17th century. During the early Romantic era, composers such as Beethoven and Mendelssohn composed overtures which were independent, self-existing, instrumental, programmatic works that foreshadowed genres such as the symphonic poem. These were "at first undoubtedly intended to be played at the head of a programme".

symphony in three movements by Wolfgang Amadeus Mozart

overture to the opera William Tell composed by Gioachino Rossini

unfinished opera by Hector Berlioz