prelude

An introductory or preliminary performance or event.

A short, free-form piece of music, originally one serving as an introduction to a longer and more complex piece; later, starting with the Romantic period, generally a stand-alone piece.

A standard module or library of subroutines and functions to be imported, generally by default, into a program.

A forerunner to anything.

To introduce something, as a prelude.

To play an introduction or prelude; to give a prefatory performance.