A prelude is something that comes before and introduces something larger or more important. In music, a prelude is a short piece played at the beginning of a concert or before a longer work, setting the mood for what follows. Bach's famous preludes prepare listeners for the more complex fugues that come after them.

The word extends beyond music to describe any introductory event or action. The dark clouds gathering in the morning might be a prelude to an afternoon thunderstorm. A few small disagreements between friends could be a prelude to a bigger argument if they don't talk things through. When countries begin moving troops toward their borders, historians sometimes recognize these actions as a prelude to conflict.

Think of a prelude as a signal or warm-up for what's coming. The way you organize your notes and sharpen your pencils might be a prelude to a serious study session. The first drops of rain are a prelude to the downpour. A prelude doesn't just happen to occur first: it actively introduces, hints at, or prepares you for the main event that follows.