‘序幕’ literally combines ‘序’ (xù), meaning ‘preface’, ‘introduction’, or ‘sequence’, and ‘幕’ (mù), meaning ‘curtain’—as in a theater curtain. Together, they evoke the image of the curtain rising to reveal the beginning of a performance: thus, ‘prologue’ or ‘opening act’. It’s a metaphorical term used not only for theater but also for the initial phase of any significant event, process, or development—such as a historical period, a project, or even a natural phenomenon.

In modern usage, ‘序幕’ often carries a formal, literary, or slightly elevated tone. It suggests something foundational yet preliminary—a harbinger of what is to come—not merely a start, but a meaningful, symbolic beginning that sets the stage. You’ll encounter it in news reports, historical narratives, academic writing, and speeches, especially when describing pivotal turning points or inaugural moments with dramatic weight.