prelude

中文： 序幕、前奏曲、前奏、过门

1. An introductory or preliminary performance or event.
2. 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.
3. A standard module or library of subroutines and functions to be imported, generally by default, into a program.
4. A forerunner to anything. (figuratively)

复数 preludes